maintainers.lenny: add github (#437479)

Changed files
+2
maintainers
+2
maintainers/maintainer-list.nix
···
lenny = {
name = "Lenny.";
+
github = "LennyPenny";
+
githubId = 4027243;
matrix = "@lenny:flipdot.org";
keys = [ { fingerprint = "6D63 2D4D 0CFE 8D53 F5FD C7ED 738F C800 6E9E A634"; } ];