Fix tag recognition when starting/ending with -

As can be found on
https://www.webforefront.com/django/usebuiltinjinjastatements.html
jinja tags can actually start and end with a `-` after resp. before the
`%` sign. This has been added to the regex.

indent/jinja.vim

@@ -1,7 +1,7 @@
 " Vim indent file
 " Language:	Jinja HTML template
 " Maintainer:	Evan Hammer <evan@evanhammer.com>
-" Last Change:	2013 Jan 26
+" Last Change:	2021 Jul 17
 
 " Only load this indent file when no other was loaded.
 if exists("b:did_indent")
@@ -50,8 +50,8 @@ function! GetDjangoIndent(...)
     let pnb = getline(lnum)
     let cur = getline(v:lnum)
 
-    let tagstart = '.*' . '{%\s*'
-    let tagend = '.*%}' . '.*'
+    let tagstart = '.*' . '{%-\?\s*'
+    let tagend = '.*-\?%}' . '.*'
 
     let blocktags = '\(block\|for\|if\|with\|autoescape\|comment\|filter\|spaceless\)'
     let midtags = '\(empty\|else\|elif\)'