tests: Move split-grid to dev dependencies

This is only used for testing.

src/package-lock.json

@@ -7936,7 +7936,8 @@
     "split-grid": {
       "version": "1.0.11",
       "resolved": "https://registry.npmjs.org/split-grid/-/split-grid-1.0.11.tgz",
-      "integrity": "sha512-ELtFtxc3r5we5GZfe6Fi0BFFxIi2M6BY1YEntBscKRDD3zx4JVHqx2VnTRSQu1BixCYSTH3MTjKd4esI2R7EgQ=="
+      "integrity": "sha512-ELtFtxc3r5we5GZfe6Fi0BFFxIi2M6BY1YEntBscKRDD3zx4JVHqx2VnTRSQu1BixCYSTH3MTjKd4esI2R7EgQ==",
+      "dev": true
     },
     "split2": {
       "version": "3.2.2",

src/package.json

@@ -65,7 +65,6 @@
     "security": "1.0.0",
     "semver": "5.7.1",
     "socket.io": "^2.4.1",
-    "split-grid": "^1.0.11",
     "terser": "^4.7.0",
     "threads": "^1.4.0",
     "tiny-worker": "^2.3.0",
@@ -94,6 +93,7 @@
     "openapi-schema-validation": "^0.4.2",
     "set-cookie-parser": "^2.4.6",
     "sinon": "^9.2.0",
+    "split-grid": "^1.0.11",
     "superagent": "^3.8.3",
     "supertest": "4.0.2",
     "wd": "1.12.1"