Update tree-sitter-git-commit (helix-editor#7831)

This fixes a problem parsing the "On branch _branch_" part of the
commit comment when the branch contains a slash.

languages.toml

@@ -1296,7 +1296,7 @@ text-width = 72
 
 [[grammar]]
 name = "git-commit"
-source = { git = "https://github.com/the-mikedavis/tree-sitter-git-commit", rev = "db88cffa3952dd2328b741af5d0fc69bdb76704f" }
+source = { git = "https://github.com/the-mikedavis/tree-sitter-git-commit", rev = "6f193a66e9aa872760823dff020960c6cedc37b3" }
 
 [[language]]
 name = "diff"