Switch chplcheck to use new files_with_stdlib_contexts

From #25326

Signed-off-by: Anna Rift <[email protected]>

tools/chplcheck/src/chplcheck.py

@@ -263,7 +263,7 @@ def main():
 
     printed_warning = False
 
-    for filename, context in chapel.files_with_contexts(args.filenames):
+    for filename, context in chapel.files_with_stdlib_contexts(args.filenames):
         context.set_module_paths([], [])
 
         # Silence errors, warnings etc. -- we're just linting.