use the conda forge implementation on the vnu-validator (#17)

* swap out old invocation with conda based invocation
* rm vnu-jar from node install

.github/test-environment.yml

@@ -28,4 +28,5 @@ dependencies:
   - scipy
   - doit
   - mkdocs-material
-  - mkdocstrings[python]
+  - mkdocstrings[python]
+  - vnu-validator

.github/workflows/test.yml

@@ -59,7 +59,7 @@ jobs:
           playwright install --with-deps chromium
       - name: init node & files
         run: |
-          npm install vnu-jar axe-core
+          npm install axe-core
           doit copy
       - name: init dev module
         run: |

tests/test_w3c.py

@@ -9,33 +9,31 @@
 import pathlib
 import re
 import shlex
+import shutil
 import subprocess
+from pathlib import Path
+
+from json import dumps
+from logging import getLogger
+from pathlib import Path
 
 import exceptiongroup
+from pytest import mark, param
+
 
 from tests.test_smoke import CONFIGURATIONS, get_target_html
 
 EXCLUDE = re.compile(
     """or with a “role” attribute whose value is “table”, “grid”, or “treegrid”.$"""
     # https://github.com/validator/validator/issues/1125
 )
-
-
-@functools.lru_cache(1)
-def vnu_jar():
-    VNU_JAR = (
-        pathlib.Path(subprocess.check_output(shlex.split("npm root vnu-jar")).strip().decode())
-        / "vnu-jar/build/dist/vnu.jar"
-    )
-    assert VNU_JAR.exists()
-    return VNU_JAR
+VNU = shutil.which("vnu") or shutil.which("vnu.cmd")
 
 
 def validate_html(*files: pathlib.Path) -> dict:
     return json.loads(
         subprocess.check_output(
-            shlex.split(f"java -jar {vnu_jar()} --stdout --format json --exit-zero-always")
-            + list(files)
+            [VNU, "--stdout", "--format", "json", "--exit-zero-always",  *files]
         ).decode()
     )
 
@@ -64,13 +62,6 @@ def raise_if_errors(results, exclude=EXCLUDE):
         raise exceptiongroup.ExceptionGroup("nu validator errors", exceptions)
 
 
-from json import dumps
-from logging import getLogger
-from pathlib import Path
-
-import exceptiongroup
-from pytest import mark, param
-
 HERE = Path(__file__).parent
 NOTEBOOKS = HERE / "notebooks"
 EXPORTS = HERE / "exports"