Replace LinkedIn icon with its last Simple Icons version pre-removal

Tabler Icons' brand-linkedin looked visually inconsistent with the
other five (different design language); Simple Icons never had a
filled-style alternative to offer since it was removed outright
(commit a9693e7259, per simple-icons#11372: LinkedIn's brand
guidelines don't permit third-party logo use). Using the last version
from simple-icons' own history (commit ea278fb, identical to what was
originally hand-authored here) restores visual consistency; the
underlying trademark caveat applies the same as it would to any
reproduction of this logo, deemed acceptable risk for a personal
site's social link icon.

templates/icons/linkedin.svg

@@ -1 +1 @@
-<svg role="img" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg" fill="currentColor" aria-hidden="true" focusable="false"><title>LinkedIn</title><path d="M17 2a5 5 0 0 1 5 5v10a5 5 0 0 1 -5 5h-10a5 5 0 0 1 -5 -5v-10a5 5 0 0 1 5 -5zm-9 8a1 1 0 0 0 -1 1v5a1 1 0 0 0 2 0v-5a1 1 0 0 0 -1 -1m6 0a3 3 0 0 0 -1.168 .236l-.125 .057a1 1 0 0 0 -1.707 .707v5a1 1 0 0 0 2 0v-3a1 1 0 0 1 2 0v3a1 1 0 0 0 2 0v-3a3 3 0 0 0 -3 -3m-6 -3a1 1 0 0 0 -.993 .883l-.007 .127a1 1 0 0 0 1.993 .117l.007 -.127a1 1 0 0 0 -1 -1"/></svg>
+<svg role="img" viewBox="0 0 24 24" xmlns="http://www.w3.org/2000/svg" fill="currentColor" aria-hidden="true" focusable="false"><title>LinkedIn</title><path d="M20.447 20.452h-3.554v-5.569c0-1.328-.027-3.037-1.852-3.037-1.853 0-2.136 1.445-2.136 2.939v5.667H9.351V9h3.414v1.561h.046c.477-.9 1.637-1.85 3.37-1.85 3.601 0 4.267 2.37 4.267 5.455v6.286zM5.337 7.433c-1.144 0-2.063-.926-2.063-2.065 0-1.138.92-2.063 2.063-2.063 1.14 0 2.064.925 2.064 2.063 0 1.139-.925 2.065-2.064 2.065zm1.782 13.019H3.555V9h3.564v11.452zM22.225 0H1.771C.792 0 0 .774 0 1.729v20.542C0 23.227.792 24 1.771 24h20.451C23.2 24 24 23.227 24 22.271V1.729C24 .774 23.2 0 22.222 0h.003z"/></svg>