[IMP] runbot_merge: make space characters in regexes clearer

pycharm is a bit dumb so it considers `[ ]` to be unnecessary even in
`re.VERBOSE` regexes. But it has a bit of a point in that it's not
super clear, so inject the space characters by (unicode) name, the
behaviour should be the exact same but the regexes should be slightly
less opaque.

Author: xmo-odoo

runbot_merge/models/stagings_create.py

@@ -691,7 +691,7 @@ def add_self_references(
         ))
 
 BREAK = re.compile(r'''
-    [ ]{0,3} # 0-3 spaces of indentation
+    \N{SPACE}{0,3} # 0-3 spaces of indentation
     # followed by a sequence of three or more matching -, _, or * characters,
     # each followed optionally by any number of spaces or tabs
     # so needs to start with a _, - or *, then have at least 2 more such
@@ -701,9 +701,9 @@ def add_self_references(
     [ \t]*
 ''', flags=re.VERBOSE)
 SETEX_UNDERLINE = re.compile(r'''
-    [ ]{0,3} # no more than 3 spaces indentation
+    \N{SPACE}{0,3} # no more than 3 spaces indentation
     [-=]+ # a sequence of = characters or a sequence of - characters
-    [ ]* # any number of trailing spaces
+    \N{SPACE}* # any number of trailing spaces
     # we don't care about "a line containing a single -" because we want to
     # disambiguate SETEX headings from thematic breaks, and thematic breaks have
     # 3+ -. Doesn't look like GH interprets `- - -` as a line so yay...