Bump downstream dependencies in CI (#14051)

Co-authored-by: pyca-boringbot[bot] <pyca-boringbot[bot][email protected]>

Author: pyca-boringbot[bot]

.github/workflows/ci.yml

@@ -463,13 +463,13 @@ jobs:
             PATH: mitmproxy
           - DOWNSTREAM: scapy
             REPO: secdev/scapy
-            # Latest commit on the scapy master branch, as of Dec 02, 2025.
-            REF: e73137ee6ce51f65f5e9c00ef771b2f42c96406b
+            # Latest commit on the scapy master branch, as of Dec 23, 2025.
+            REF: 9c3d51c148090c3f2d4774714efae9e69e4d7f8f
             PATH: scapy
           - DOWNSTREAM: sigstore-python
             REPO: sigstore/sigstore-python
-            # Latest commit on the sigstore-python main branch, as of Dec 20, 2025.
-            REF: 93e8c86ddd7cc9e2dd6243ec7470e5ff11794e9d
+            # Latest commit on the sigstore-python main branch, as of Dec 23, 2025.
+            REF: 524df83642a3247d98d846458d92beb81b6c284a
             PATH: sigstore-python
     name: "Downstream tests for ${{ matrix.DOWNSTREAM }}"
     timeout-minutes: 15