Add a filter for tags.

docker_tags_getter/filters/tags_filter.py

@@ -0,0 +1,13 @@
+import re
+
+class TagsFilter:
+    def __init__(self):
+        self._pattern = r'-\D\w+'
+        self.regexp = re.compile(self._pattern)
+
+    def check(self):
+        return lambda tag: len(self.regexp.findall(tag)) == 0
+
+    def filter_list(self, tags: list):
+        return list(filter(self.check(), tags))
+