fix(readme): image version

Fernans96 · Fernans96 · commit 20d11e7d4164 · 2017-08-09T16:40:02.000+02:00
diff --git a/README.md b/README.md
@@ -5,7 +5,7 @@ This is a C/C++ runner for CMake projects (based on GCC).
 ## How to Use it
 
 ```yaml
-runner: techio/cmake-gcc-runner:1.1.0-gcc-6.3
+runner: techio/cmake-gcc-runner:1.1.0-gcc-7.1
 ```
 
 Your project will be compiled one with:
