Remove version pin for grpcio-tools.

`robotframework-browser` has this and a few others hardcoded in their `requirements.txt`.
See https://github.com/MarketSquare/robotframework-browser/blob/main/Browser/requirements.txt
They hardcode a few version numbers to keep their CI matrix from bloating.

As long as they do that, we do not need to specify these versions ourselves.
We already have no version pin for their `grpcio` and `protobuf` dependencies.
These dependencies both end up in `bin/test`, and Buildout does not complain about missing version pins, so it is fine.

versions-extra.cfg

@@ -20,7 +20,6 @@ distro = 1.9.0
 fancycompleter = 0.9.1
 filelock = 3.13.4
 gitdb = 4.0.11
-grpcio-tools = 1.66.1
 GitPython = 3.1.43
 httplib2 = 0.22.0
 i18ndude = 6.2.1
@@ -70,7 +69,3 @@ zestreleaser.towncrier = 1.3.0
 zodbverify = 1.2.0
 zope.mkzeoinstance = 5.1.1
 ZopeUndo = 6.0
-
-[versionannotations]
-grpcio-tools =
-    Requirement of robotframework-browser: grpcio-tools==1.66.1