Fix php version for alpine

Author: mblaschke

tests/serverspec/spec/spec_helper.rb

@@ -44,7 +44,7 @@
     (os[:family] == 'redhat' and os[:version] == '7') or
     (os[:family] == 'debian' and os[:version] == '7') or
     (os[:family] == 'debian' and os[:version] == '8') or
-    (os[:family] == 'alpine' and os[:version] == '8') or
+    (os[:family] == 'alpine' and os[:version] == '3') or
     ($dockerInfo[:tag].match('php5')))
     $testConfiguration[:php] = 5
 end