default shell is bash, not pwsh

.github/workflows/build.yml

@@ -430,6 +430,7 @@ jobs:
           cp dist/win/contrib/* appdir/Cryptomator
       - name: Fix permissions
         run: attrib -r appdir/Cryptomator/Cryptomator.exe
+        shell: pwsh
       - name: Codesign
         uses: skymatic/code-sign-action@v1.0.1
         with:
@@ -457,6 +458,7 @@ jobs:
           --win-dir-chooser `
           --resource-dir dist/win/resources `
           --license-file dist/win/resources/license.rtf
+        shell: pwsh
       - name: Codesign MSI
         uses: skymatic/code-sign-action@v1.0.1
         with: