chore(deps): bump brotli from 1.1.0 to 1.2.0 in /src/loadgenerator (GoogleCloudPlatform#3154)

Bumps [brotli](https://github.com/google/brotli) from 1.1.0 to 1.2.0.
- [Release notes](https://github.com/google/brotli/releases)
- [Changelog](https://github.com/google/brotli/blob/master/CHANGELOG.md)
- [Commits](google/brotli@go/cbrotli/v1.1.0...v1.2.0)

---
updated-dependencies:
- dependency-name: brotli
  dependency-version: 1.2.0
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

src/loadgenerator/requirements.txt

@@ -8,7 +8,7 @@ bidict==0.23.1
     # via python-socketio
 blinker==1.9.0
     # via flask
-brotli==1.1.0
+brotli==1.2.0
     # via geventhttpclient
 certifi==2025.8.3
     # via