Bump vue-apollo from 3.0.0-rc.2 to 3.0.0-rc.6 in /js

Bumps [vue-apollo](https://github.com/Akryum/vue-apollo) from 3.0.0-rc.2 to 3.0.0-rc.6.
- [Release notes](https://github.com/Akryum/vue-apollo/releases)
- [Commits](https://github.com/Akryum/vue-apollo/compare/v3.0.0-rc.2...v3.0.0-rc.6)

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

js/package.json

@@ -30,7 +30,7 @@
     "tiptap-extensions": "^1.20.1",
     "typeface-signika": "0.0.72",
     "vue": "^2.6.10",
-    "vue-apollo": "^3.0.0-rc.1",
+    "vue-apollo": "^3.0.0-rc.6",
     "vue-class-component": "^7.0.2",
     "vue-i18n": "^8.14.0",
     "vue-property-decorator": "^8.1.0",