Bump minimatch from 3.0.4 to 3.1.2 in /generator-exercise

Bumps [minimatch](https://github.com/isaacs/minimatch) from 3.0.4 to 3.1.2.
- [Release notes](https://github.com/isaacs/minimatch/releases)
- [Commits](https://github.com/isaacs/minimatch/compare/v3.0.4...v3.1.2)

---
updated-dependencies:
- dependency-name: minimatch
  dependency-type: indirect
...

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

generator-exercise/package-lock.json

@@ -3199,9 +3199,9 @@
       "dev": true
     },
     "minimatch": {
-      "version": "3.0.4",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
-      "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
+      "version": "3.1.2",
+      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
+      "integrity": "sha512-J7p63hRiAjw1NDEww1W7i37+ByIrOWO5XQQAzZ3VOcL0PNybwpfmV/N05zFAzwQ9USyEcX6t3UO+K5aqBQOIHw==",
       "requires": {
         "brace-expansion": "^1.1.7"
       }