Update gemspec, bump version, and fix comment

Gemfile.lock

@@ -1,8 +1,8 @@
 PATH
   remote: .
   specs:
-    calligraphy (0.3.0)
-      rails (~> 5.0)
+    calligraphy (0.3.1)
+      rails (~> 5.0, >= 5.0)
 
 GEM
   remote: https://rubygems.org/
@@ -65,7 +65,7 @@ GEM
     mini_mime (1.0.0)
     mini_portile2 (2.3.0)
     minitest (5.10.3)
-    nio4r (2.1.0)
+    nio4r (2.2.0)
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     parallel (1.12.1)
@@ -156,11 +156,11 @@ PLATFORMS
 DEPENDENCIES
   calligraphy!
   pry-nav
-  puma (~> 3.11.0)
-  rake (~> 12.3.0)
-  rspec-rails (~> 3.7.2)
+  puma (~> 3.11.0, >= 3.11.0)
+  rake (~> 12.3.0, >= 12.3.0)
+  rspec-rails (~> 3.7.2, >= 3.7.2)
   rubocop (~> 0.52.1)
-  sqlite3 (~> 1.3.13)
+  sqlite3 (~> 1.3.13, >= 1.3.13)
 
 BUNDLED WITH
    1.16.1