Update protobuf to 5.29.5 to address security vulnerability (#525)

## Problem

The Pinecone Python client is currently using protobuf version `^5.29`,
which includes vulnerable versions that are affected by
[GHSA-8qvm-5x2c-j2w7](GHSA-8qvm-5x2c-j2w7).
This vulnerability involves uncontrolled recursion in Protobuf's
pure-Python backend, which could lead to Denial of Service (DoS)
attacks.

## Solution

Updated the protobuf dependency constraint from `^5.29` to `^5.29.5` to
ensure we're using the patched version that addresses this security
vulnerability. The changes include:

- Updated `pyproject.toml`: Changed protobuf version constraint from
`^5.29` to `^5.29.5`
- Updated `testing-dependency-grpc.yaml`: Updated protobuf version from
`5.29.1` to `5.29.5` in all three dependency testing matrix
configurations
- Verified that `poetry.lock` already contains protobuf 5.29.5, so no
additional lock file updates were needed

This is a patch version update, so no breaking changes are expected. The
protobuf dependency is optional and only installed when the `grpc` extra
is requested.

**Note:** This is a security patch release to address the immediate
vulnerability for existing users. A future release will include a
comprehensive update to protobuf 6.x, which may include breaking changes
and will require more extensive testing and migration planning.


## Type of Change

- [X] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] This change requires a documentation update
- [ ] Infrastructure change (CI configs, etc)
- [ ] Non-code change (docs, etc)
- [ ] None of the above: (explain here)

## Test Plan

- Verified protobuf 5.29.5 is already installed and working
- Updated CI/CD pipeline to test with the new version
- No breaking changes expected as this is a patch version update

Author: rohanshah18

.github/workflows/testing-dependency-grpc.yaml

@@ -44,7 +44,7 @@ jobs:
           # - 4.1.0
           - 4.3.3
         protobuf_version:
-          - 5.29.1
+          - 5.29.5
         protoc-gen-openapiv2:
           - 0.0.1
         googleapis_common_protos_version:
@@ -83,7 +83,7 @@ jobs:
           # - 3.1.3
           - 4.3.3
         protobuf_version:
-          - 5.29.1
+          - 5.29.5
         protoc-gen-openapiv2:
           - 0.0.1
         googleapis_common_protos_version:
@@ -121,7 +121,7 @@ jobs:
           # - 3.1.3
           - 4.3.3
         protobuf_version:
-          - 5.29.1
+          - 5.29.5
         protoc-gen-openapiv2:
           - 0.0.1
         googleapis_common_protos_version: