Drop tests for Python 3.6 on Windows

No longer supported by action actions/setup-python#355 (comment)

.github/workflows/release.yml

@@ -573,7 +573,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
     steps:
       - uses: actions/checkout@v2
       - name: Set version env
@@ -604,7 +604,7 @@ jobs:
       matrix:
         # Skip 3.10 due to a broken python link.
         # Turn back on after this is resolved https://github.com/pypa/cibuildwheel/issues/902
-        python-version: ["3.6", "3.7", "3.8", "3.9"]
+        python-version: ["3.7", "3.8", "3.9"]
     steps:
       - uses: actions/checkout@v2
       - name: Set version env
@@ -699,7 +699,7 @@ jobs:
     runs-on: windows-latest
     strategy:
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
     steps:
       - uses: actions/checkout@v2
       - name: Set version env
@@ -728,7 +728,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.7", "3.8", "3.9", "3.10"]
     steps:
       - uses: actions/checkout@v2
       - name: Set version env