Add koa as peerDeps and fix the encoding option propagation (#160)

## Description

Fix #155 and #157

## Checklist

- [x] I have ensured my pull request is not behind the main or master
branch of the original repository.
- [x] I have rebased all commits where necessary so that reviewing this
pull request can be done without having to merge it first.
- [x] I have written a commit message that passes commitlint linting.
- [x] I have ensured that my code changes pass linting tests.
- [x] I have ensured that my code changes pass unit tests.
- [x] I have described my pull request and the reasons for code changes
along with context if necessary.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@koa/bodyparser",
-  "version": "5.1.0",
+  "version": "5.1.1",
   "description": "Koa body parsing middleware",
   "main": "./dist/index.js",
   "module": "./dist/index.mjs",
@@ -69,6 +69,9 @@
     "lodash.merge": "^4.6.2",
     "type-is": "^1.6.18"
   },
+  "peerDependencies": {
+    "koa": "^2.14.1"
+  },
   "engines": {
     "node": ">= 16"
   },

src/body-parser.ts

@@ -66,6 +66,8 @@ export function bodyParserWrapper(opts: BodyParserOptions = {}) {
       strict: bodyType === 'json' ? restOpts.jsonStrict : undefined,
       [`${bodyType}Types`]: mimeTypes[bodyType],
       limit: restOpts[`${shouldParseBodyAs('xml') ? 'xml' : bodyType}Limit`],
+      // eslint-disable-next-line unicorn/text-encoding-identifier-case
+      encoding: restOpts.encoding || 'utf-8',
     };
 
     return parser[bodyType](ctx, parserOptions) as Promise<

test/middleware.test.ts

@@ -56,7 +56,7 @@ describe("test/body-parser.test.ts", () => {
         .expect({ foo: "bar" });
     });
 
-    it.only("should parse json body with `content-type: application/json;charset=utf-8;` headers ok", async () => {
+    it("should parse json body with `content-type: application/json;charset=utf-8;` headers ok", async () => {
       app.use(bodyParser());
 
       app.use(async (ctx) => {