fix: ignore_case in pattern_matching_skill (#477)

* fix: ignore_case in pattern_matching_skill

* fix: do not lowercase None pattern

* fix: lowecase only nonregex patterns

deeppavlov/skills/pattern_matching_skill/pattern_matching_skill.py

@@ -11,11 +11,16 @@ def __init__(self, responses, patterns=None, regex=False, ignore_case=True):
         self.responses = responses
         if isinstance(patterns, str):
             patterns = [patterns]
-        if patterns and regex:
-            patterns = [re.compile(pattern) for pattern in patterns]
-        self.patterns = patterns
         self.regex = regex
         self.ignore_case = ignore_case
+        if regex:
+            if patterns:
+                flags = re.IGNORECASE if ignore_case else 0
+                patterns = [re.compile(pattern, flags) for pattern in patterns]
+        else:
+            if patterns and ignore_case:
+                patterns = [pattern.lower() for pattern in patterns]
+        self.patterns = patterns
 
     def __call__(self, utterances_batch, history_batch, states_batch):
         response = [random.choice(self.responses) for _ in utterances_batch]