Fix regular expression for = rule

Bug reported by @cvlmtg

autoload/easy_align.vim

@@ -31,7 +31,7 @@ set cpo&vim
 
 let s:easy_align_delimiters_default = {
 \  ' ': { 'pattern': ' ',  'left_margin': 0, 'right_margin': 0, 'stick_to_left': 0 },
-\  '=': { 'pattern': '===\|<=>\|\(&&\|||\|<<\|>>\)=\|=\~[#?]\?\|=>\|[:+/*!%^=><&|.-?]\?=[#?]\?',
+\  '=': { 'pattern': '===\|<=>\|\(&&\|||\|<<\|>>\)=\|=\~[#?]\?\|=>\|[:+/*!%^=><&|.?-]\?=[#?]\?',
 \                          'left_margin': 1, 'right_margin': 1, 'stick_to_left': 0 },
 \  ':': { 'pattern': ':',  'left_margin': 0, 'right_margin': 1, 'stick_to_left': 1 },
 \  ',': { 'pattern': ',',  'left_margin': 0, 'right_margin': 1, 'stick_to_left': 1 },

test/fixed.vader

@@ -201,7 +201,7 @@ Expect:
 * #65 ?=
 Given:
   a?=b
-  aa?=bb
+  aa-=bb
   aaa?=bbb
 
 Do (#65 Alignment around ?=):
@@ -209,7 +209,7 @@ Do (#65 Alignment around ?=):
 
 Expect:
   a   ?= b
-  aa  ?= bb
+  aa  -= bb
   aaa ?= bbb
 
 Include: include/teardown.vader