build: fix peer deps

BREAKING CHANGE: VueFire is compatible only with Vue `^2.7.0 || ^3.2.0`,
it **cannot work with `@vue/composition-api`** (which is natively included
on `vue@>=2.7.0`). Note VueFire also requires `firebase@^9.0.0`.

Author: posva

Diff for: package.json

@@ -55,9 +55,8 @@
     "vue-demi": "latest"
   },
   "peerDependencies": {
-    "@vue/composition-api": "^1.4.0",
     "firebase": "^9.0.0",
-    "vue": "^2.6.0 || >=3.2.0"
+    "vue": "^2.7.0 || ^3.2.0"
   },
   "peerDependenciesMeta": {
     "firebase": {