Stop using shell=True in subprocess

Change-Id: Iefd0a4942c16d9aee44cfe61c746083c2e2bd3b9
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2099446
Tested-by: Allen Li <ayatane@chromium.org>
Auto-Submit: Allen Li <ayatane@chromium.org>
Commit-Queue: Prathmesh Prabhu <pprabhu@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 69956a4..203b117 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -5,13 +5,11 @@
 def CheckGenerated(input_api, output_api):
   results = []
   input_api.subprocess.call(
-      './generate.sh',
-      shell=True,
+      ['bash', './generate.sh'],
       stdout=input_api.subprocess.PIPE,
       stderr=input_api.subprocess.PIPE)
   if input_api.subprocess.call(
-      'git diff --exit-code',
-      shell=True,
+      ['git', 'diff', '--exit-code'],
       stdout=input_api.subprocess.PIPE,
       stderr=input_api.subprocess.PIPE) != 0:
     msg = ('Running generate.sh produced a diff. Please '