Increasing timeout for cache

MIPS is regularly timing out when updating the cache.
diff --git a/.travis.yml b/.travis.yml
index 6f6e725..0af6c9d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,7 @@
 sudo: false
 
 cache:
+  timeout: 1000
   directories:
     - $HOME/cpu_features_archives