Fix regular expression

diff --git a/.travis.yml b/.travis.yml
index a1e8219..259be95 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,4 +11,4 @@ after_script: bash release.sh -g 7.3.5

 branches:
   only:
-  - /^[vV]0?\d+\.\d+(\.\d+)?(-\S*)?$/
+  - /^[vV]?\d+\.\d+(\.\d+)?(-\S*)?$/