Update Travis CI to use PHP 8.0snapshot instead of 8.0.0

tortuetorche · tortuetorche · commit 79f6cd4b4b66 · 2020-12-01T14:02:50.000+01:00
Because it's still unavailable on Travis CI...
diff --git a/.travis.yml b/.travis.yml
@@ -4,7 +4,7 @@ php:
   - 7.2
   - 7.3
   - 7.4
-  - 8.0.0
+  - 8.0snapshot
 
 matrix:
   fast_finish: true
