CI: Enable testing on Windows

Author: amotl

.github/workflows/main.yml

@@ -20,7 +20,7 @@ jobs:
     strategy:
       matrix:
         crate-version: [nightly]
-        os: [ubuntu-latest, macos-latest]
+        os: [ubuntu-latest, macos-latest, windows-latest]
         sqla-version: ['1.1.18', '1.2.19', '1.3.20']
         python-version: [3.5, 3.6, 3.7, 3.8, 3.9]
 
@@ -57,7 +57,7 @@ jobs:
           bin/flake8
 
           test_program=bin/test
-          if [ ${{ matrix.os }} = "macos-latest" ]; then
+          if [ ${{ matrix.os }} = "macos-latest" || ${{ matrix.os }} = "windows-latest" ]; then
             test_program=bin/test-quick
           fi
           bin/coverage run $test_program -vv1