.travs.yml: Use ghc-7.10.3 instead of 7.10.2

Ghc 7.10.2 changed the show instance for Float/Double which causes
test that passed with other GHC versions, failed with ghc-7.10.2.

Author: erikd

.travis.yml

@@ -3,7 +3,7 @@ sudo: false
 env:
   - CABALVER=1.18 GHCVER=7.6.3
   - CABALVER=1.18 GHCVER=7.8.4
-  - CABALVER=1.22 GHCVER=7.10.2
+  - CABALVER=1.22 GHCVER=7.10.3
   - CABALVER=1.24 GHCVER=8.0.1
 
 addons:
@@ -13,7 +13,7 @@ addons:
     packages:
       - ghc-7.6.3
       - ghc-7.8.4
-      - ghc-7.10.2
+      - ghc-7.10.3
       - ghc-8.0.1
       - cabal-install-1.18
       - cabal-install-1.22