hugo: add git as a dependency

Hugo needs Git to find meta informations such as the pubDate

images/hugo/default.nix

@@ -1,6 +1,8 @@
 { buildCLIImage
 , hugo
+, gitReallyMinimal
 }:
 buildCLIImage {
   drv = hugo;
+  extraContents = [ gitReallyMinimal ];
 }