Update peerDeps to allow prettier v4. (#210)

I've been using the v4 alphas of prettier for a *very long time*, and
they have always worked just fine with this plugin.

---------

Co-authored-by: Ian VanSchooten <ian.vanschooten@gmail.com>

Author: cpojer

package.json

@@ -77,7 +77,7 @@
     },
     "peerDependencies": {
         "@vue/compiler-sfc": "2.7.x || 3.x",
-        "prettier": "2 || 3"
+        "prettier": "2 || 3 || ^4.0.0-0"
     },
     "peerDependenciesMeta": {
         "@vue/compiler-sfc": {