Bump downstream dependencies in CI (#15258)

Co-authored-by: pyca-boringbot[bot] <pyca-boringbot[bot]+106132319@users.noreply.github.com>

Author: pyca-boringbot[bot]

.github/workflows/ci.yml

@@ -416,8 +416,8 @@ jobs:
             PATH: pyopenssl
           - DOWNSTREAM: twisted
             REPO: twisted/twisted
-            # Latest commit on the twisted trunk branch, as of Jul 07, 2026.
-            REF: fe27ab1dae3236564f720beaeb73258ee93cd78a
+            # Latest commit on the twisted trunk branch, as of Jul 14, 2026.
+            REF: a0915042088f684cd697e3e6c5dce79c7045d386
             PATH: twisted
           - DOWNSTREAM: aws-encryption-sdk-python
             REPO: awslabs/aws-encryption-sdk-python
@@ -436,8 +436,8 @@ jobs:
             PATH: josepy
           - DOWNSTREAM: mitmproxy
             REPO: mitmproxy/mitmproxy
-            # Latest commit on the mitmproxy main branch, as of Jul 03, 2026.
-            REF: a67fc64596c472cb468be6b3ac188511e8e9ff94
+            # Latest commit on the mitmproxy main branch, as of Jul 14, 2026.
+            REF: cca8d91b5681d7bc4f5fd465957326ec8d33eb83
             PATH: mitmproxy
           - DOWNSTREAM: scapy
             REPO: secdev/scapy
@@ -446,8 +446,8 @@ jobs:
             PATH: scapy
           - DOWNSTREAM: sigstore-python
             REPO: sigstore/sigstore-python
-            # Latest commit on the sigstore-python main branch, as of Jul 09, 2026.
-            REF: f7342c66f294bf48988f89268df243b77c71db8f
+            # Latest commit on the sigstore-python main branch, as of Jul 14, 2026.
+            REF: 07572fa3109014f7f70b3ff19524524354f6ef70
             PATH: sigstore-python
     name: "Downstream tests for ${{ matrix.DOWNSTREAM }}"
     timeout-minutes: 15