Build with Python 3.8 on Windows

.github/workflows/package.yml

@@ -104,10 +104,10 @@ jobs:
       with:
         fetch-depth: 0  # Fetch entire history, needed for setting the build number
     - run: git fetch --depth=1 origin +refs/tags/release-*:refs/tags/release-*
-    - name: Set up Python 3.7
+    - name: Set up Python 3.8
       uses: actions/setup-python@v1
       with:
-        python-version: 3.7
+        python-version: 3.8
     - name: Setup Windows build environment
       run: |
         & .\scripts\package\win-setup.ps1 -DiscidVersion $Env:DISCID_VERSION -FpcalVersion $Env:FPCALC_VERSION