.github: use ps archive command

Since the `zip` utility is not available in the used build container,
updating to use the available `Compress-Archive` cmdlet.

Signed-off-by: James Knight <james.d.knight@live.com>

.github/workflows/release.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Create archive
         run: |
           cd output/staging
-          zip -r capsblock-portable.zip .
+          Compress-Archive -Path * -Destination capsblock-portable.zip
 
       - name: Generate hashes
         run: |