Use windows-2019 for tests in GitHub Actions

For the time being let's just use the older version for the GHA host, so
we can keep testing on Windows, instead of skipping it at all.

Author: abravalheri

.github/workflows/main.yml

@@ -24,7 +24,7 @@ jobs:
         platform:
         - ubuntu-latest
         - macos-latest
-        - windows-latest
+        - windows-2019
         include:
         - platform: ubuntu-latest
           python: "3.10"

tox.ini

@@ -20,17 +20,13 @@ passenv =
 	windir  # required for test_pkg_resources
 	# honor git config in pytest-perf
 	HOME
-	PROGRAMFILES
-	PROGRAMFILES(x86)
 
 [testenv:integration]
 deps = {[testenv]deps}
 extras = testing-integration
 passenv =
 	{[testenv]passenv}
 	DOWNLOAD_PATH
-	PROGRAMFILES
-	PROGRAMFILES(x86)
 setenv =
     PROJECT_ROOT = {toxinidir}
 commands =