First check ignores then check cache

This gives you the possibility to add a errornous migration
to the ignore list. On the seccond run the linter will
first use the ignore list and not the cache first.

django_migration_linter/migration_linter.py

@@ -96,15 +96,15 @@ class MigrationLinter(object):
 
         md5hash = self.get_migration_hash(app_label, migration_name)
 
-        if self.should_use_cache() and md5hash in self.old_cache:
-            self.lint_cached_migration(md5hash)
-            return
-
         if self.should_ignore_migration(app_label, migration_name):
             print("IGNORE")
             self.nb_ignored += 1
             return
 
+        if self.should_use_cache() and md5hash in self.old_cache:
+            self.lint_cached_migration(md5hash)
+            return
+
         sql_statements = self.get_sql(app_label, migration_name)
         analysis_result = analyse_sql_statements(sql_statements)
         errors = analysis_result["errors"]