Merge pull request #58 from slackapi/dependabot/pip/flask-1.0

Bump flask from 0.12.3 to 1.0

Author: seratch

requirements.txt

@@ -1,6 +1,6 @@
 appdirs==1.4.0
 pyee==5.0.0
-flask==0.12.3
+flask==1.0
 packaging==16.8
 pyparsing==2.1.10
 six==1.10.0