Add angular v8 - 12 as peer deps (#46)

Author: ashinzekene

projects/angular4-paystack/package.json

@@ -2,8 +2,8 @@
   "name": "angular4-paystack",
   "version": "3.0.1",
   "peerDependencies": {
-    "@angular/common": "^8.0.3",
-    "@angular/core": "^8.0.3"
+    "@angular/common": "8.0.3 - 12.*",
+    "@angular/core": "8.0.3 - 12.*"
   },
   "repository": {
     "type": "git",