Bump downstream dependencies in CI (#13881)

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

Author: pyca-boringbot[bot]

.github/workflows/ci.yml

@@ -458,8 +458,8 @@ jobs:
             PATH: josepy
           - DOWNSTREAM: mitmproxy
             REPO: mitmproxy/mitmproxy
-            # Latest commit on the mitmproxy main branch, as of Nov 14, 2025.
-            REF: 26074879818ed547d3ca44b02880fb78ee62bbb3
+            # Latest commit on the mitmproxy main branch, as of Nov 15, 2025.
+            REF: 08a947bd6787959a711f660486bb801ab90b9388
             PATH: mitmproxy
           - DOWNSTREAM: scapy
             REPO: secdev/scapy
@@ -468,8 +468,8 @@ jobs:
             PATH: scapy
           - DOWNSTREAM: sigstore-python
             REPO: sigstore/sigstore-python
-            # Latest commit on the sigstore-python main branch, as of Nov 14, 2025.
-            REF: ddeaedaf13a4a58e6180a4bdf78b091fe76373a4
+            # Latest commit on the sigstore-python main branch, as of Nov 15, 2025.
+            REF: 26413931a784a3a355bd76dd9f87db5081758904
             PATH: sigstore-python
     name: "Downstream tests for ${{ matrix.DOWNSTREAM }}"
     timeout-minutes: 15