home: git: add 'ignoreRevsFile'

I'm surprised I hadn't configured it already.

`.git-blame-ignore-revs` is the usual name, as most forges automatically
detect and use it.

modules/home/git/default.nix

@@ -75,6 +75,7 @@ in
       # Makes it a bit more readable
       blame = {
         coloring = "repeatedLines";
+        ignoreRevsFile = ".git-blame-ignore-revs";
         markIgnoredLines = true;
         markUnblamables = true;
       };