CI: common.run_pmbootstrap: use simple check=True (MR 5633)

Use check=True instead of running check_returncode() afterwards, it has
the same effect and is shorter.

.ci/lib/common.py

@@ -47,8 +47,7 @@ def commit_message_has_string(needle):
 def run_pmbootstrap(parameters):
     """ Run pmbootstrap with the pmaports dir as --aports """
     cmd = ["pmbootstrap", "--aports", get_pmaports_dir()] + parameters
-    result = subprocess.run(cmd, universal_newlines=True)
-    result.check_returncode()
+    subprocess.run(cmd, universal_newlines=True, check=True)
 
 
 def get_upstream_branch():