Add support for slashes and colons in class names

This is to add support for [Tailwind CSS](https://tailwindcss.com/)

lib/slim/parser.rb

@@ -70,7 +70,7 @@ def initialize(opts = {})
         end
       end
       keys = Regexp.union @attr_shortcut.keys.sort_by {|k| -k.size }
-      @attr_shortcut_re = /\A(#{keys}+)((?:\p{Word}|-)*)/
+      @attr_shortcut_re = /\A(#{keys}+)((?:\p{Word}|-|\/\d+|:(\w|-)+)*)/
       keys = Regexp.union @tag_shortcut.keys.sort_by {|k| -k.size }
       @tag_re = /\A(?:#{keys}|\*(?=[^\s]+)|(\p{Word}(?:\p{Word}|:|-)*\p{Word}|\p{Word}+))/
       keys = Regexp.escape @code_attr_delims.keys.join

test/literate/TESTS.md

@@ -1186,13 +1186,15 @@ renders to
 
 #### ID shortcut and class shortcut `.`
 
-ID and class shortcuts can contain dashes.
+ID and class shortcuts can contain dashes, slashes with digits, and colons.
 
 ~~~ slim
 .-test text
 #test- text
 .--a#b- text
 .a--test-123#--b text
+.a-1/2#b-1/2 text
+.ab:c-test#d:e text
 ~~~
 
 renders as
@@ -1210,6 +1212,12 @@ renders as
 <div class="a--test-123" id="--b">
   text
 </div>
+<div class="a-1/2" id="b-1/2">
+  text
+</div>
+<div class="ab:c-test" id="d:e">
+  text
+</div>
 ~~~
 
 ## Text interpolation