ci: remove Docker credentials (public image)

Author: danrmiller

.github/workflows/release.yml

@@ -11,9 +11,6 @@ jobs:
     runs-on: ubuntu-24.04
     container:
       image: stackwallet/stackwallet-ci:latest
-      credentials:
-        username: ${{ secrets.DOCKERHUB_USERNAME }}
-        password: ${{ secrets.DOCKERHUB_TOKEN }}
     strategy:
       matrix:
         include:
@@ -53,9 +50,6 @@ jobs:
     runs-on: ubuntu-24.04
     container:
       image: stackwallet/stackwallet-ci:latest
-      credentials:
-        username: ${{ secrets.DOCKERHUB_USERNAME }}
-        password: ${{ secrets.DOCKERHUB_TOKEN }}
     strategy:
       matrix:
         include:
@@ -191,9 +185,6 @@ jobs:
     runs-on: ubuntu-24.04
     container:
       image: stackwallet/stackwallet-ci:latest
-      credentials:
-        username: ${{ secrets.DOCKERHUB_USERNAME }}
-        password: ${{ secrets.DOCKERHUB_TOKEN }}
     steps:
       - uses: actions/checkout@v4