Upgrade yapf to 0.20.0

Upgrade yapf version to 0.20.0 and reformat Python files.
diff --git a/tools/run_tests/run_tests_matrix.py b/tools/run_tests/run_tests_matrix.py
index 49be8f1..ac90bef 100755
--- a/tools/run_tests/run_tests_matrix.py
+++ b/tools/run_tests/run_tests_matrix.py
@@ -65,8 +65,10 @@
     test_job = jobset.JobSpec(
         cmdline=[
             'python', 'tools/run_tests/run_tests.py', '--use_docker', '-t',
-            '-j', str(inner_jobs), '-x', _report_filename(name),
-            '--report_suite_name', '%s' % name
+            '-j',
+            str(inner_jobs), '-x',
+            _report_filename(name), '--report_suite_name',
+            '%s' % name
         ] + runtests_args,
         environ=runtests_envs,
         shortname='run_tests_%s' % name,
@@ -90,8 +92,10 @@
     test_job = jobset.JobSpec(
         cmdline=[
             'bash', 'tools/run_tests/helper_scripts/run_tests_in_workspace.sh',
-            '-t', '-j', str(inner_jobs), '-x', '../%s' % _report_filename(name),
-            '--report_suite_name', '%s' % name
+            '-t', '-j',
+            str(inner_jobs), '-x',
+            '../%s' % _report_filename(name), '--report_suite_name',
+            '%s' % name
         ] + runtests_args,
         environ=env,
         shortname='run_tests_%s' % name,
@@ -492,8 +496,8 @@
 
     jobs = []
     for job in all_jobs:
-        if not args.filter or all(filter in job.labels
-                                  for filter in args.filter):
+        if not args.filter or all(
+                filter in job.labels for filter in args.filter):
             if not any(exclude_label in job.labels
                        for exclude_label in args.exclude):
                 jobs.append(job)