Fix the staging release process (#1373)

### Motivation

The "Build and inspect an artifact." step in the [release process](https://github.com/apache/pulsar-client-go/blob/master/docs/release-process.md) would also include the `.git` folder.

https://lists.apache.org/thread/pndqy7lfb8nrsgjh0wfq1bsrs1g7ds3y


### Modifications

- Added a new script for staging the release artifact: `stag-release.sh`
- Updated the release process to exclude the `.git` folder from the release artifact

Author: RobertIndie

docs/release-process.md

@@ -51,19 +51,10 @@ git push origin v0.X.0-candidate-1
 
 3. Build and inspect an artifact.
 
-Generate a release candidate package.
+Stage and sign the release artifacts.
 
 ```bash
-$ tar -zcvf apache-pulsar-client-go-0.X.0-src.tar.gz .
-```
-
-4. Sign and stage the artifacts 
-
-The src artifact need to be signed and uploaded to the dist SVN repository for staging.
-
-```
-$ gpg -b --armor apache-pulsar-client-go-0.X.0-src.tar.gz
-$ shasum -a 512 apache-pulsar-client-go-0.X.0-src.tar.gz > apache-pulsar-client-go-0.X.0-src.tar.gz.sha512 
+$ ./scripts/stage-release.sh 0.X.0 .
 ```
 
 Checkout repo for uploading artifacts

scripts/stage-release.sh

@@ -0,0 +1,43 @@
+#!/bin/bash
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+set -euo pipefail
+
+if [ $# -ne 2 ]; then
+    echo "Usage: $0 <version> <destination_directory>"
+    exit 1
+fi
+
+VERSION=$1
+
+DEST_PATH=$2
+DEST_PATH="$(cd "$DEST_PATH" && pwd)"
+
+pushd "$(dirname "$0")"
+REPO_PATH=$(git rev-parse --show-toplevel)
+popd
+
+pushd "$REPO_PATH"
+git archive --format=tar.gz --output="$DEST_PATH/apache-pulsar-client-go-$VERSION-src.tar.gz" HEAD
+popd
+
+# Sign all files
+cd "$DEST_PATH"
+gpg -b --armor apache-pulsar-client-go-$VERSION-src.tar.gz
+shasum -a 512 apache-pulsar-client-go-$VERSION-src.tar.gz > apache-pulsar-client-go-$VERSION-src.tar.gz.sha512
+