chore: downgrade docs protobuf version (#9380)

Author: bshaffer

.github/workflows/docs.yaml

@@ -17,7 +17,7 @@ jobs:
       uses: actions/setup-python@v7
       with:
         python-version: '3.14'
-    - run: pip install --no-deps --require-hashes -r .kokoro/docs/docker/requirements.txt
+    - run: pip install --require-hashes -r .kokoro/docs/docker/requirements.txt
     - name: Setup PHP
       uses: shivammathur/setup-php@verbose
       with:

.kokoro/docs/docker/requirements.txt

@@ -341,15 +341,17 @@ proto-plus==1.28.1 \
     # via
     #   -r requirements.in
     #   google-api-core
-protobuf==7.35.1 \
-    --hash=sha256:11d6b0ec246892d85215b0a13ca6e0233cf5284b68f0ac02646427f4ff88a799 \
-    --hash=sha256:230a75ddfc2de4806e56696ce9640c1cdfdb6543b7cfce98d42a4c0a0e7bdb87 \
-    --hash=sha256:24f857477359a85c0c235261b8ba905fd51b2562f4a64ca1df5473f29850cbf6 \
-    --hash=sha256:353652e4efd0bca5b5fc2656abf8307ef351f0cf938c9eba09f0e09c20a25c30 \
-    --hash=sha256:4bc97768d8fe4ad6743c8a19403e314511ed9f6d13205b687e52421c023ac1b9 \
-    --hash=sha256:74758715c53d7158fb76caf4f0cfdacc5329a4b1bb994f865d6cf302d413a1c4 \
-    --hash=sha256:b73f9489a4b8b1c9cb1f8ed951c736392592edb24b9d6819f36d2e10b171d5b4 \
-    --hash=sha256:ce115a26fe0c39a2c29973d914d327e516a6455464489fe3cd1e51a1b354f81a
+protobuf==6.33.6 \
+    --hash=sha256:0cd27b587afca21b7cfa59a74dcbd48a50f0a6400cfb59391340ad729d91d326 \
+    --hash=sha256:77179e006c476e69bf8e8ce866640091ec42e1beb80b213c3900006ecfba6901 \
+    --hash=sha256:7d29d9b65f8afef196f8334e80d6bc1d5d4adedb449971fefd3723824e6e77d3 \
+    --hash=sha256:9720e6961b251bde64edfdab7d500725a2af5280f3f4c87e57c0208376aa8c3a \
+    --hash=sha256:a6768d25248312c297558af96a9f9c929e8c4cee0659cb07e780731095f38135 \
+    --hash=sha256:bd56799fb262994b2c2faa1799693c95cc2e22c62f56fb43af311cae45d26f0e \
+    --hash=sha256:c96c37eec15086b79762ed265d59ab204dabc53056e3443e702d2681f4b39ce3 \
+    --hash=sha256:e2afbae9b8e1825e3529f88d514754e094278bb95eadc0e199751cdd9a2e82a2 \
+    --hash=sha256:e9db7e292e0ab79dd108d7f1a94fe31601ce1ee3f7b79e0692043423020b0593 \
+    --hash=sha256:f443a394af5ed23672bc6c486be138628fbe5c651ccbc536873d7da23d1868cf
     # via
     #   gcp-docuploader
     #   google-api-core