Fix missing syntax highlighting on code snippets (#283)

The artifact.language is unset on standard files that are not stdin.
This change properly sets it to the lexer value of the parser.`

Signed-off-by: Eric Brown <eric.brown@securesauce.dev>

precli/core/run.py

@@ -118,6 +118,7 @@ def parse_file(
                     ),
                     None,
                 )
+                artifact.language = parser.lexer
 
             if parser is not None:
                 LOG.debug("Working on file: %s", artifact.file_name)