Remove scan dependencies workflow

We're not using these anywhere and instead we rely on GitHub's own
security scanning features which means we don't need to maintain our own
workflows.

Author: thomasleese

.github/actions/scan-dependencies/action.yaml

@@ -73,22 +73,3 @@ jobs:
           fetch-depth: 0 # Full history is needed to compare branches
       - name: "Check English usage"
         uses: ./.github/actions/check-english-usage
-  scan-dependencies:
-    name: "Scan dependencies"
-    runs-on: ubuntu-latest
-    permissions:
-      id-token: write
-      contents: read
-    timeout-minutes: 2
-    steps:
-      - name: "Checkout code"
-        uses: actions/checkout@v4
-      - name: "Scan dependencies"
-        uses: ./.github/actions/scan-dependencies
-        with:
-          build_datetime: "${{ inputs.build_datetime }}"
-          build_timestamp: "${{ inputs.build_timestamp }}"
-          idp_aws_report_upload_account_id: "${{ secrets.IDP_AWS_REPORT_UPLOAD_ACCOUNT_ID }}"
-          idp_aws_report_upload_region: "${{ secrets.IDP_AWS_REPORT_UPLOAD_REGION }}"
-          idp_aws_report_upload_role_name: "${{ secrets.IDP_AWS_REPORT_UPLOAD_ROLE_NAME }}"
-          idp_aws_report_upload_bucket_endpoint: "${{ secrets.IDP_AWS_REPORT_UPLOAD_BUCKET_ENDPOINT }}"

.github/workflows/stage-1-commit.yaml

@@ -5,8 +5,6 @@ python 3.13.3
 # The section below is reserved for Docker image versions.
 
 # TODO: Move this section - consider using a different file for the repository template dependencies.
-# docker/ghcr.io/anchore/grype v0.69.1@sha256:d41fcb371d0af59f311e72123dff46900ebd6d0482391b5a830853ee4f9d1a76 # SEE: https://github.com/anchore/grype/pkgs/container/grype
-# docker/ghcr.io/anchore/syft v0.92.0@sha256:63c60f0a21efb13e80aa1359ab243e49213b6cc2d7e0f8179da38e6913b997e0 # SEE: https://github.com/anchore/syft/pkgs/container/syft
 # docker/ghcr.io/gitleaks/gitleaks v8.18.0@sha256:fd2b5cab12b563d2cc538b14631764a1c25577780e3b7dba71657d58da45d9d9 # SEE: https://github.com/gitleaks/gitleaks/pkgs/container/gitleaks
 # docker/ghcr.io/igorshubovych/markdownlint-cli v0.37.0@sha256:fb3e79946fce78e1cde84d6798c6c2a55f2de11fc16606a40d49411e281d950d # SEE: https://github.com/igorshubovych/markdownlint-cli/pkgs/container/markdownlint-cli
 # docker/ghcr.io/make-ops-tools/gocloc latest@sha256:6888e62e9ae693c4ebcfed9f1d86c70fd083868acb8815fe44b561b9a73b5032 # SEE: https://github.com/make-ops-tools/gocloc/pkgs/container/gocloc