fix(core): don't lock nodemailer version as peer dependency

Author: balazsorban44

packages/core/package.json

@@ -69,7 +69,7 @@
     "preact-render-to-string": "5.2.3"
   },
   "peerDependencies": {
-    "nodemailer": "6.8.0"
+    "nodemailer": "^6.8.0"
   },
   "peerDependenciesMeta": {
     "nodemailer": {
@@ -92,4 +92,4 @@
     "postcss": "8.4.19",
     "postcss-nested": "6.0.0"
   }
-}
+}