travis: Limit git depth to 5 commits

We don't need 50 commits for our purposes, so might as well save some
bandwidth and possibly some time by making the clone shallower.
Signed-off-by: NAndrea Bolognani <abologna@redhat.com>
Reviewed-by: NDaniel P. Berrange <berrange@redhat.com>

.travis.yml

@@ -57,6 +57,7 @@ notifications:
       - secure: "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"
 
 git:
+  depth: 5
   submodules: true
 
 before_install: