Bumpt luatest version 0.5.4

Changes are available in [1].

1. tarantool/luatest@0.5.4...master

Author: ligurio

deps.sh

@@ -4,7 +4,7 @@
 set -e
 
 # Test dependencies:
-tarantoolctl rocks install luatest 0.5.3
+tarantoolctl rocks install luatest 0.5.4
 tarantoolctl rocks install luacheck 0.25.0
 tarantoolctl rocks install luacov 0.13.0