Update git-utils to version 2.6.2

Version 2.6.2 is used by atom core.
This fixes build with up-to-date node.js

Author: yuri-per

.travis.yml

@@ -15,4 +15,4 @@ addons:
   apt:
     packages:
     - build-essential
-    - clang-3.3
+    - clang-5.0

package-lock.json

@@ -21,7 +21,7 @@
   "homepage": "http://atom.github.io/scandal",
   "dependencies": {
     "argparse": "^1.0.2",
-    "git-utils": "^5.6.0",
+    "git-utils": "5.6.2",
     "isbinaryfile": "^2.0.4",
     "minimatch": "^2.0.9",
     "split": "^1.0.0",