ci: update authentication to use GITEA_TOKEN for secure Git operations

- Replace GITEA_PASSWORD with GITEA_TOKEN in environment variables
- Add validation checks for GITEA_USERNAME and GITEA_TOKEN
- Update git remote URL to include token for authentication
- Simplify push command to use configured origin remote

This change enhances security by using a token instead of a password for Git authentication in the CI pipeline.

.drone.yml

@@ -48,15 +48,18 @@ steps:
     environment:
       GITEA_USERNAME:
         from_secret: gitea_username
-      GITEA_PASSWORD:
+      GITEA_TOKEN:
         from_secret: gitea_password
     commands:
       - apk add --no-cache git sed
+      - test -n "$GITEA_USERNAME"
+      - test -n "$GITEA_TOKEN"
       - git clone https://gitea.mnky-code.de/mnky/k8s-manifests.git
       - cd k8s-manifests
+      - git remote set-url origin "https://${GITEA_USERNAME}:${GITEA_TOKEN}@gitea.mnky-code.de/mnky/k8s-manifests.git"
       - 'sed -i "s|image: gitea.mnky-code.de/mnky/ngrx-playground:.*|image: gitea.mnky-code.de/mnky/ngrx-playground:${DRONE_COMMIT_SHA}|" ngrx-playground/deployment.yaml'
       - git config user.name "drone"
       - git config user.email "drone@mnky-code.de"
       - git add ngrx-playground/deployment.yaml
       - 'git commit -m "Deploy ngrx-playground ${DRONE_COMMIT_SHA}" || exit 0'
-      - 'git push https://${GITEA_USERNAME}:${GITEA_PASSWORD}@gitea.mnky-code.de/mnky/k8s-manifests.git HEAD:main'
+      - git push origin HEAD:main