Use dates instead of tags for plugin build names

This makes more sense for this repo, since tags are plugin-specific and
this repo bundles multiple plugins.

.github/workflows/build.yml

@@ -88,7 +88,8 @@ jobs:
 
       - name: Determine build archive name
         run: |
-          echo "ARCHIVE_NAME=nih-plugs-$(git describe --always)-${{ matrix.name }}" >> "$GITHUB_ENV"
+          # Windows (usually) doesn't like colons in file names
+          echo "ARCHIVE_NAME=nih-plugs-$(date -u +"%Y-%m-%d-%H%m%S")-${{ matrix.name }}" >> "$GITHUB_ENV"
       - name: Move all packaged plugin into a directory
         run: |
           # GitHub Action strips the top level directory, great, have another one