Catch Slack webhook with 10 char (Yelp#325)

We were getting report that slack custom application webhook will contain a different foramt
for webhooks. In particualar the B+8 chars could become B+10 chars format

User reprot https://ibm-cio-gi.slack.com/archives/CDMGJ9QG2/p1591018601323500?thread_ts=1590777088.301300&cid=CDMGJ9QG2

We also noticed the response error message is differnet, this commit tried to address that issue and allow us to catch webhook for custom Slack applications

detect_secrets/plugins/slack.py

@@ -19,21 +19,24 @@ class SlackDetector(RegexBasedDetector):
         # Slack Webhooks
         re.compile(
             r"""
-            https://hooks.slack.com/services/T[a-zA-Z0-9_]{8}/B[a-zA-Z0-9_]{8}/[a-zA-Z0-9_]{24}
+            https://hooks.slack.com/services/T[a-zA-Z0-9_]{8}/B[a-zA-Z0-9_]{8,10}/[a-zA-Z0-9_]{24}
             """,
             flags=re.IGNORECASE | re.VERBOSE,
         ),
     )
 
-    def verify(self, token, **kwargs):  # pragma: no cover
+    def verify(self, token, *args, **kwargs):  # pragma: no cover
         if token.startswith('https://hooks.slack.com/services/T'):
             response = requests.post(
                 token,
                 json={
                     'text': '',
                 },
             )
-            valid = response.text == 'missing_text_or_fallback_or_attachments'
+            valid = (
+                response.text == 'missing_text_or_fallback_or_attachments'
+                or response.text == 'no_text'
+            )
         else:
             response = requests.post(
                 'https://slack.com/api/auth.test',

tests/plugins/slack_test.py

@@ -33,6 +33,9 @@ class TestSlackDetector:
             (
                 'https://hooks.slack.com/services/Txxxxxxxx/Bxxxxxxxx/xxxxxxxxxxxxxxxxxxxxxxxx'
             ),
+            (
+                'https://hooks.slack.com/services/Txxxxxxxx/Bxxxxxxxxxx/xxxxxxxxxxxxxxxxxxxxxxxx'
+            ),
         ],
     )
     def test_analyze(self, file_content):