Workaround GitHub Actions limits

Due to this [1] it seems impossible to run the container as an unprivileged
user, so we override with root.

[1] actions/checkout#1014

Author: rascasoft

.github/workflows/main.yml

@@ -10,6 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: quay.io/mmul/kpa
+      options: --user root
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
@@ -28,6 +29,7 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: quay.io/mmul/kpa
+      options: --user root
     needs: lint
     steps:
       - name: Checkout repository
@@ -54,6 +56,7 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: quay.io/mmul/kpa
+      options: --user root
     needs: markdown
     steps:
       - name: Checkout repository