Use the modern auth for ghcr within actions

https://docs.github.com/en/actions/publishing-packages/publishing-docker-images#publishing-images-to-docker-hub-and-github-packages
(cherry picked from commit 2efc311)

Author: HoloRin

.github/workflows/oci.yaml

@@ -29,7 +29,7 @@ jobs:
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
-          password: ${{ secrets.GHCR_TOKEN }}
+          password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Set up QEMU
         uses: docker/setup-qemu-action@v3

.github/workflows/test-authnz.yaml

@@ -52,7 +52,7 @@ jobs:
       with:
         registry: ghcr.io
         username: ${{ github.actor }}
-        password: ${{ secrets.GHCR_TOKEN }}
+        password: ${{ secrets.GITHUB_TOKEN }}
 
     - name: Configure OTP & Elixir
       uses: erlef/[email protected]

.github/workflows/test-selenium.yaml

@@ -49,7 +49,7 @@ jobs:
       with:
         registry: ghcr.io
         username: ${{ github.actor }}
-        password: ${{ secrets.GHCR_TOKEN }}
+        password: ${{ secrets.GITHUB_TOKEN }}
 
     - name: Configure OTP & Elixir
       uses: erlef/[email protected]