Bump ruby version to 2.7.4

Especially since I can't seem to install ruby 2.6.4 on my M1 Mac...

Author: AliSoftware

.ruby-version

@@ -1 +1 @@
-2.6.4
+2.7.4

Gemfile.lock

@@ -271,6 +271,7 @@ GEM
     method_source (0.9.2)
     mini_magick (4.11.0)
     mini_mime (1.1.2)
+    mini_portile2 (2.8.0)
     minitest (5.14.4)
     molinillo (0.8.0)
     multi_json (1.15.0)
@@ -280,7 +281,8 @@ GEM
     naturally (2.2.1)
     netrc (0.11.0)
     no_proxy_fix (0.1.2)
-    nokogiri (1.13.3-x86_64-darwin)
+    nokogiri (1.13.3)
+      mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
     octokit (4.21.0)
       faraday (>= 0.9)
@@ -435,4 +437,4 @@ DEPENDENCIES
   yard
 
 BUNDLED WITH
-   2.3.13
+   2.3.16