Revert tiptap upgrade

- it introduced a bug that caused failing tests
- I have found an open issue on the repo and commented what I experienced here https://github.com/scrumpy/tiptap/issues/188#issuecomment-490532736

webapp/package.json

@@ -18,7 +18,10 @@
   "jest": {
     "verbose": true,
     "collectCoverage": true,
-    "coverageReporters": ["text", "lcov"],
+    "coverageReporters": [
+      "text",
+      "lcov"
+    ],
     "moduleFileExtensions": [
       "js",
       "json",
@@ -53,8 +56,8 @@
     "nuxt-env": "~0.1.0",
     "stack-utils": "^1.0.2",
     "string-hash": "^1.1.3",
-    "tiptap": "^1.18.0",
-    "tiptap-extensions": "^1.18.1",
+    "tiptap": "1.17.0",
+    "tiptap-extensions": "1.17.0",
     "v-tooltip": "~2.0.2",
     "vue-count-to": "~1.0.13",
     "vue-izitoast": "1.1.2",