Downgrade graphiql to v3.8.3

Something broke in v3.9.0

Signed-off-by: Timo Sand <timo.sand@f-secure.com>

plugins/api-docs/package.json

@@ -66,7 +66,7 @@
     "@material-ui/core": "^4.12.2",
     "@material-ui/icons": "^4.9.1",
     "@material-ui/lab": "4.0.0-alpha.61",
-    "graphiql": "^3.9.0",
+    "graphiql": "^3.8.3",
     "graphql": "^16.0.0",
     "graphql-config": "^5.0.2",
     "graphql-ws": "^5.4.1",