Use main branch from calibreapp/image-actions

Signed-off-by: yubiuser <github@yubiuser.dev>

Author: yubiuser

.github/workflows/calibreapp-image-actions.yml

@@ -21,6 +21,6 @@ jobs:
           persist-credentials: false
 
       - name: Compress Images
-        uses: calibreapp/image-actions@1.1.0 # TODO: if they start using a tag like v1, switch to that
+        uses: calibreapp/image-actions@main # Their latest tag is > 4 years old and the README says to use main
         with:
           githubToken: ${{ secrets.GITHUB_TOKEN }}