pyproject.toml: limit pysnmp's pyasn1 dependency to <0.6.0

pysnmp depends on pyasn1. `pyasn1.compat.octets` was removed in pyasn1
0.6.1 [1] leading to ModuleNotFoundErrors in labgrid's "eaton" and
"poe_mib" power backends:

  _______________ TestNetworkPowerDriver.test_import_backend_eaton _______________

  self = <test_powerdriver.TestNetworkPowerDriver object at 0x7f84794bfdd0>

      def test_import_backend_eaton(self):
          pytest.importorskip("pysnmp")
  >       import labgrid.driver.power.eaton

  tests/test_powerdriver.py:295:
  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
  labgrid/driver/power/eaton.py:2: in <module>
      from ...util.snmp import SimpleSNMP
  labgrid/util/snmp.py:1: in <module>
      from pysnmp import hlapi
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/hlapi/__init__.py:7: in <module>
      from pysnmp.proto.rfc1902 import *
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/proto/rfc1902.py:8: in <module>
      from pysnmp.proto import rfc1155, error
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/proto/rfc1155.py:10: in <module>
      from pysnmp.proto import error
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/proto/error.py:9: in <module>
      from pysnmp import debug
  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

      #
      # This file is part of pysnmp software.
      #
      # Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
      # License: https://www.pysnmp.com/pysnmp/license.html
      #
      import logging
  >   from pyasn1.compat.octets import octs2ints
  E   ModuleNotFoundError: No module named 'pyasn1.compat.octets'

  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/debug.py:8: ModuleNotFoundError
  ______________ TestNetworkPowerDriver.test_import_backend_poe_mib ______________

  self = <test_powerdriver.TestNetworkPowerDriver object at 0x7f84794bd910>

      def test_import_backend_poe_mib(self):
          pytest.importorskip("pysnmp")
  >       import labgrid.driver.power.poe_mib

  tests/test_powerdriver.py:307:
  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
  labgrid/driver/power/poe_mib.py:4: in <module>
      from ...util.snmp import SimpleSNMP
  labgrid/util/snmp.py:1: in <module>
      from pysnmp import hlapi
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/hlapi/__init__.py:7: in <module>
      from pysnmp.proto.rfc1902 import *
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/proto/rfc1902.py:8: in <module>
      from pysnmp.proto import rfc1155, error
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/proto/rfc1155.py:10: in <module>
      from pysnmp.proto import error
  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/proto/error.py:9: in <module>
      from pysnmp import debug
  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

      #
      # This file is part of pysnmp software.
      #
      # Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
      # License: https://www.pysnmp.com/pysnmp/license.html
      #
      import logging
  >   from pyasn1.compat.octets import octs2ints
  E   ModuleNotFoundError: No module named 'pyasn1.compat.octets'

  /opt/hostedtoolcache/Python/3.12.5/x64/lib/python3.12/site-packages/pysnmp/debug.py:8: ModuleNotFoundError

The issue is documented upstream [2]. [3] limited the pysnmp version to
<6. pysnmp 6.1.4, 6.2.6, and 7.1.0 are not affected.

For stable, limit compatible pyasn1 versions to <0.6.1. On master, [5]
switches labgrid to pysnmp's asyncio API, thereby dropping the upper
bound introduced by [3].

[1] https://github.com/pyasn1/pyasn1/releases/tag/v0.6.1
[2] pyasn1/pyasn1#76
[3] labgrid-project#1332
[4] lextudio/pysnmp#113 (comment)
[5] labgrid-project#1497

Signed-off-by: Bastian Krause <bst@pengutronix.de>

pyproject.toml

@@ -69,7 +69,10 @@ pyvisa = [
     "pyvisa>=1.11.3",
     "PyVISA-py>=0.5.2",
 ]
-snmp = ["pysnmp-lextudio>=4.4.12, <6"]
+snmp = [
+    "pysnmp-lextudio>=4.4.12, <6",
+    "pyasn1<0.6.1",
+]
 vxi11 = ["python-vxi11>=0.9"]
 xena = ["xenavalkyrie>=3.0.1"]
 deb = [
@@ -81,6 +84,7 @@ deb = [
 
     # labgrid[snmp]
     "pysnmp-lextudio>=4.4.12, <6",
+    "pyasn1<0.6.1",
 ]
 dev = [
     # references to other optional dependency groups
@@ -115,6 +119,7 @@ dev = [
 
     # labgrid[snmp]
     "pysnmp-lextudio>=4.4.12, <6",
+    "pyasn1<0.6.1",
 
     # labgrid[vxi11]
     "python-vxi11>=0.9",