Fixing bash path problem, avoiding 'docker-compose-completion.sh: bash: bad interpreter: No such file or directory' error

Signed-off-by: Allan de Queiroz <[email protected]>

contrib/completion/bash/docker-compose

@@ -1,4 +1,4 @@
-#!bash
+#!/bin/bash
 #
 # bash completion for docker-compose
 #