Bump gitlog from 3.1.2 to 4.0.4

Bumps [gitlog](https://github.com/domharrington/node-gitlog) from 3.1.2 to 4.0.4.
- [Release notes](https://github.com/domharrington/node-gitlog/releases)
- [Changelog](https://github.com/domharrington/node-gitlog/blob/master/CHANGELOG.md)
- [Commits](domharrington/node-gitlog@v3.1.2...v4.0.4)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

package-lock.json

@@ -21,7 +21,7 @@
   "homepage": "https://github.com/dronsfield/commit-viewer#readme",
   "dependencies": {
     "express": "^4.16.3",
-    "gitlog": "^3.1.2",
+    "gitlog": "^4.0.4",
     "lodash": "^4.17.21",
     "mkdirp": "^0.5.1",
     "moment": "^2.22.0",