deps: update dependency google-api-core to v2.12.0 (#2153)

Author: renovate-bot

.kokoro/requirements.txt

@@ -135,9 +135,9 @@ gcp-releasetool==1.16.0 \
     --hash=sha256:27bf19d2e87aaa884096ff941aa3c592c482be3d6a2bfe6f06afafa6af2353e3 \
     --hash=sha256:a316b197a543fd036209d0caba7a8eb4d236d8e65381c80cbc6d7efaa7606d63
     # via -r requirements.in
-google-api-core==2.8.2 \
-    --hash=sha256:06f7244c640322b508b125903bb5701bebabce8832f85aba9335ec00b3d02edc \
-    --hash=sha256:93c6a91ccac79079ac6bbf8b74ee75db970cc899278b97d53bc012f35908cf50
+google-api-core==2.12.0 \
+    --hash=sha256:c22e01b1e3c4dcd90998494879612c38d0a3411d1f7b679eb89e2abe3ce1f553 \
+    --hash=sha256:ec6054f7d64ad13b41e43d96f735acbd763b0f3b695dabaa2d579673f6a6e160
     # via
     #   google-cloud-core
     #   google-cloud-storage