chore(deps): update dependency keyring to v25.6.0

Author: renovate-bot

.kokoro/requirements.txt

@@ -360,9 +360,9 @@ jinja2==3.1.4 \
     --hash=sha256:4a3aee7acbbe7303aede8e9648d13b8bf88a429282aa6122a993f0ac800cb369 \
     --hash=sha256:bc5dd2abb727a5319567b7a813e6a2e7318c39f4f487cfe6c89c6f9c7d25197d
     # via gcp-releasetool
-keyring==25.5.0 \
-    --hash=sha256:4c753b3ec91717fe713c4edd522d625889d8973a349b0e582622f49766de58e6 \
-    --hash=sha256:e67f8ac32b04be4714b42fe84ce7dad9c40985b9ca827c592cc303e7c26d9741
+keyring==25.6.0 \
+    --hash=sha256:0b39998aa941431eb3d9b0d4b2460bc773b9df6fed7621c2dfb291a7e0187a66 \
+    --hash=sha256:552a3f7af126ece7ed5c89753650eec89c7eaae8617d0aa4d9ad2b75111266bd
     # via
     #   gcp-releasetool
     #   twine