Support the last two Next/React majors in peer deps

Update mailing's peerDependencies to next@^15 || ^16 and
react/react-dom@^18 || ^19 (from next@^12-14, react@^17-18), matching the
versions the e2e matrix now runs and removing peer-dep warnings on current
Next.js/React. Changeset included.

Author: psugihara

.changeset/next-react-peer-range.md

@@ -0,0 +1,5 @@
+---
+"mailing": minor
+---
+
+Update peer dependency ranges to the last two major versions of the frameworks mailing supports: `next@^15 || ^16` and `react`/`react-dom@^18 || ^19` (previously `next@^12–14`, `react@^17–18`). This removes peer-dependency warnings for projects on current Next.js and React, which the e2e matrix now exercises.

packages/cli/package.json

@@ -42,9 +42,9 @@
     "node-mocks-http": "^1.11.0"
   },
   "peerDependencies": {
-    "next": "^12.0.0 || ^13.0.0 || ^14.0.0",
-    "react": "^17.0.0 || ^18.0.0",
-    "react-dom": "^17.0.0 || ^18.0.0"
+    "next": "^15.0.0 || ^16.0.0",
+    "react": "^18.0.0 || ^19.0.0",
+    "react-dom": "^18.0.0 || ^19.0.0"
   },
   "dependencies": {
     "@babel/parser": "^7.18.11",