test(dm): update python2 to python3

Makefile

@@ -442,7 +442,7 @@ dm_integration_test_build_ctl: check_failpoint_ctl
 
 install_test_python_dep:
 	@echo "install python requirments for test"
-	pip install --user -q -r ./dm/tests/requirements.txt
+	pip3 install --user -q -r ./dm/tests/requirements.txt
 
 check_third_party_binary_for_dm:
 	@which bin/tidb-server

dm/tests/README.md

@@ -20,7 +20,7 @@
 2. The following programs must be installed:
 
     * `mysql` (the CLI client, currently [not supported for mysql client 8.0](https://github.com/pingcap/tidb/issues/14021))
-    * `python2.7` or `python3.x`
+    * `python3.x`
 
 3. The user executing the tests must have permission to create the folder `/tmp/dm_test`. All test artifacts will be written into this folder.
 

dm/tests/_utils/check_grafana_dashboard_datasource

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import sys
 import json
 

dm/tests/_utils/check_port

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 #coding: utf-8
 
 import sys

dm/tests/_utils/check_ticker_interval

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 import sys
 
 

dm/tests/openapi/client/openapi_cluster_check

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import sys
 import time
 import requests

dm/tests/openapi/client/openapi_source_check

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 import sys
 import requests
 import ssl

dm/tests/openapi/client/openapi_task_check

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 import sys
 import requests