[SPARK-43890][CONNECT][BUILD] Upgrade buf to v1.20.0

### What changes were proposed in this pull request?
The pr aims to upgrade buf from 1.19.0 to 1.20.0

### Why are the changes needed?
1.Release Notes: https://github.com/bufbuild/buf/releases, improvment as follow:
- Add --emit-defaults flag to buf curl to emit default values in JSON-encoded responses.
- Indent JSON-encoded responses from buf curl by default.
- Log a warning in case an import statement does not point to a file in the module, a file in a direct dependency, or a well-known type file.

2.bufbuild/buf@v1.19.0...v1.20.0

3.Manually test: dev/connect-gen-protos.sh, this upgrade will not change the generated files.

### Does this PR introduce _any_ user-facing change?
No.

### How was this patch tested?
- Manually test
- Pass GA

Closes apache#41394 from panbingkun/SPARK-43890.

Authored-by: panbingkun <pbk1982@gmail.com>
Signed-off-by: Ruifeng Zheng <ruifengz@apache.org>

.github/workflows/build_and_test.yml

@@ -616,7 +616,7 @@ jobs:
     - name: Install dependencies for Python code generation check
       run: |
         # See more in "Installation" https://docs.buf.build/installation#tarball
-        curl -LO https://github.com/bufbuild/buf/releases/download/v1.19.0/buf-Linux-x86_64.tar.gz
+        curl -LO https://github.com/bufbuild/buf/releases/download/v1.20.0/buf-Linux-x86_64.tar.gz
         mkdir -p $HOME/buf
         tar -xvzf buf-Linux-x86_64.tar.gz -C $HOME/buf --strip-components 1
         python3.9 -m pip install 'protobuf==3.19.5' 'mypy-protobuf==3.3.0'

python/docs/source/development/contributing.rst

@@ -120,7 +120,7 @@ Prerequisite
 
 PySpark development requires to build Spark that needs a proper JDK installed, etc. See `Building Spark <https://spark.apache.org/docs/latest/building-spark.html>`_ for more details.
 
-Note that if you intend to contribute to Spark Connect in Python, ``buf`` version ``1.19.0`` is required, see `Buf Installation <https://docs.buf.build/installation>`_ for more details.
+Note that if you intend to contribute to Spark Connect in Python, ``buf`` version ``1.20.0`` is required, see `Buf Installation <https://docs.buf.build/installation>`_ for more details.
 
 Conda
 ~~~~~