use a non-twitter URL when testing snap creation

.travis.yml

@@ -28,7 +28,7 @@ matrix:
         - sudo apt update
         - snapcraft --destructive-mode
         - sudo snap try
-        - snap run gallery-dl --verbose https://twitter.com/ubuntu/status/1121001597092364288
+        - snap run gallery-dl --verbose https://en.wikipedia.org/static/images/project-logos/enwiki.png
   allow_failures:
     - env: GALLERYDL_TESTS=results
     - env: GALLERYDL_TESTS=snap

test/test_results.py

@@ -312,6 +312,7 @@ def setup_test_config():
     config.set(("extractor", "e621")      , "username", None)
     config.set(("extractor", "instagram") , "username", None)
     config.set(("extractor", "twitter")   , "username", None)
+    config.set(("extractor", "twitter")   , "retries" , 10)
 
     config.set(("extractor", "newgrounds"), "username", "d1618111")
     config.set(("extractor", "newgrounds"), "password", "d1618111")