Update i18n plugin.

Author: kattni

BeeWare.lektorproject

@@ -83,7 +83,7 @@ locale = fa_IR
 lektor-github-repos = 0.1.1
 lektor-gravatar = 0.1.3
 lektor-markdown-admonition = 0.3.1
-git+https://github.com/beeware/lektor-i18n-plugin@v0.5.0 =
+git+https://github.com/beeware/lektor-i18n-plugin@v0.5.1 =
 
 [servers.ghpages]
 target = ghpages://beeware/beeware.github.io?cname=beeware.org