Remove auth for dependency graph action (#2849)

The dependency graph action used to update dependabot with Scala deps, no longer needs to authenticate itself in AWS as packages are pulled from Sonatype, not S3. 

The role it used has been deleted: wellcomecollection/aws-account-infrastructure#38, so this action now fails.

Removing the auth step should fix it.

Author: kenoir

Diff for: .github/workflows/dependency-graph.yml

@@ -18,8 +18,4 @@ jobs:
       - name: Install sbt
         uses: sbt/setup-sbt@v1
       - uses: actions/checkout@v3
-      - uses: aws-actions/configure-aws-credentials@v4
-        with:
-          aws-region: eu-west-1
-          role-to-assume: ${{ secrets.S3_SCALA_RELEASES_READ_ROLE_ARN }}
       - uses: scalacenter/sbt-dependency-submission@v2