cleanup: drop redundant character escapes outside of `[]`
Flagged by PyCharm. `@`, `:`, `<`, `>`, and `{` aren't special characters.
(I'm a bit surprised that it doesn't also want to unescape `}` in schemes.py.)
Differential Revision: https://phab.mercurial-scm.org/D7767
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}