build(deps): bump protobuf from 3.17.3 to 5.29.6 in /udf/agent/py2

Bumps [protobuf](https://github.com/protocolbuffers/protobuf) from 3.17.3 to 5.29.6.
- [Release notes](https://github.com/protocolbuffers/protobuf/releases)
- [Commits](https://github.com/protocolbuffers/protobuf/commits)

---
updated-dependencies:
- dependency-name: protobuf
  dependency-version: 5.29.6
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

udf/agent/py2/setup.py

@@ -14,7 +14,7 @@
         'kapacitor.udf',
     ],
     install_requires=[
-        "protobuf==3.17.3",
+        "protobuf==5.29.6",
     ],
     maintainer_email="[email protected]",
     license="MIT",