ci: bump actions/cache from 4 to 5 (#749)

Author: dependabot[bot]

.github/workflows/security-audit.yml

@@ -17,7 +17,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - name: Cache cargo bin
-        uses: actions/cache@v4
+        uses: actions/cache@v5
         with:
           path: ~/.cargo/bin
           key: ${{ runner.os }}-cargo-audit-v0.20-ubuntu-v24.04