MINOR: Adjust 'release.py' script to use shell when using gradlewAll and PGP signing, which were required to build the 2.6.0 RCs (#9045)

release.py

@@ -595,7 +595,7 @@ params = { 'release_version': release_version,
            }
 cmd("Creating source archive", "git archive --format tar.gz --prefix kafka-%(release_version)s-src/ -o %(artifacts_dir)s/kafka-%(release_version)s-src.tgz %(rc_tag)s" % params)
 
-cmd("Building artifacts", "./gradlew clean && ./gradlewAll releaseTarGz", cwd=kafka_dir, env=jdk8_env)
+cmd("Building artifacts", "./gradlew clean && ./gradlewAll releaseTarGz", cwd=kafka_dir, env=jdk8_env, shell=True)
 cmd("Copying artifacts", "cp %s/core/build/distributions/* %s" % (kafka_dir, artifacts_dir), shell=True)
 cmd("Building docs", "./gradlew aggregatedJavadoc", cwd=kafka_dir, env=jdk8_env)
 cmd("Copying docs", "cp -R %s/build/docs/javadoc %s" % (kafka_dir, artifacts_dir))
@@ -631,8 +631,8 @@ with open(os.path.expanduser("~/.gradle/gradle.properties")) as f:
     contents = f.read()
 if not user_ok("Going to build and upload mvn artifacts based on these settings:\n" + contents + '\nOK (y/n)?: '):
     fail("Retry again later")
-cmd("Building and uploading archives", "./gradlewAll uploadArchives", cwd=kafka_dir, env=jdk8_env)
-cmd("Building and uploading archives", "mvn deploy -Pgpg-signing", cwd=streams_quickstart_dir, env=jdk8_env)
+cmd("Building and uploading archives", "./gradlewAll uploadArchives", cwd=kafka_dir, env=jdk8_env, shell=True)
+cmd("Building and uploading archives", "mvn deploy -Pgpg-signing", cwd=streams_quickstart_dir, env=jdk8_env, shell=True)
 
 release_notification_props = { 'release_version': release_version,
                                'rc': rc,