chore(ci): remove gitleaks job — requires paid org license

gitleaks-action v2 requires a GITLEAKS_LICENSE secret for GitHub
organisation repos.  Remove the job rather than suppress it.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: h4x0r

.github/workflows/ci.yml

@@ -57,17 +57,6 @@ jobs:
       - uses: Swatinem/rust-cache@9d47c6ad4b02e050fd481d890b2ea34778fd09d6 # v2.7.8
       - run: cargo test --lib --test e2e_dftt
 
-  secrets:
-    name: Secret Scan (gitleaks)
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
-        with:
-          fetch-depth: 0
-      - uses: gitleaks/gitleaks-action@83373cf2f8c4db6e24b41c1a9b086bb9619e9cd3 # v2.3.7
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-
   geiger:
     name: Unsafe Audit (cargo-geiger)
     runs-on: ubuntu-latest