Update to ruby-magic v0.5.4

There are no code changes here, but the main difference is to fix a
problem with the release package that failed to include:

1. The tarball for libfile.
2. A patch to disable building of documentation and tests for libfile.

This should make installs more reliable and avoid the need for
downloading from a remote mirror.

Relates to https://github.com/kwilczynski/ruby-magic/issues/28

Diff: https://my.diffend.io/gems/ruby-magic/0.5.3/0.5.4

Changelog: changed

Gemfile.lock

@@ -1119,7 +1119,7 @@ GEM
       rubocop-ast (>= 0.7.1)
     ruby-fogbugz (0.2.1)
       crack (~> 0.4)
-    ruby-magic (0.5.3)
+    ruby-magic (0.5.4)
       mini_portile2 (~> 2.6)
     ruby-prof (1.3.1)
     ruby-progressbar (1.11.0)