CI: Only test against SQLAlchemy 1.3.20 on Windows

SQLAlchemy release series 1.1.x and 1.2.x apparently don't work on Win.

Author: amotl

.github/workflows/main.yml

@@ -64,6 +64,6 @@ jobs:
           if [[ ${{ matrix.os }} = "macos-latest" ]]; then
             bin/coverage run bin/test-quick -vv1
           fi
-          if [[ ${{ matrix.os }} = "windows-latest" && ${{ matrix.sqla-version }} != "1.1.18" ]]; then
+          if [[ ${{ matrix.os }} = "windows-latest" && ${{ matrix.sqla-version }} = "1.3.20" ]]; then
             bin/test-quick -vv1
           fi