"esmodule" key not respected in v15.0.0 #963

> yarn run v1.22.19
$ npm-run-all --parallel build:*
$ microbundle --cwd packages/api --tsconfig packages/api/tsconfig.json --target web --format modern,cjs && cp -l packages/api/dist/api/src/mod.d.ts packages/api/dist/mod.d.ts
$ microbundle --cwd packages/cli --tsconfig packages/cli/tsconfig.json --target node --format modern
Build "cli" to dist:
      6.28 kB: main.mjs.gz
      5.57 kB: main.mjs.br
Build "api" to dist:
      1.81 kB: mod.cjs.gz
       1.6 kB: mod.cjs.br
       1140 B: mod.mjs.gz
        978 B: mod.mjs.br
Done in 6.98s.

> exa -al packages/*/dist
packages/api/dist:
drwxr-xr-x    - xyz 19 May 11:05 api
drwxr-xr-x    - xyz 19 May 11:05 lib
.rw-r--r-- 5.5k xyz 19 May 11:05 mod.cjs
.rw-r--r--  12k xyz 19 May 11:05 mod.cjs.map
.rw-r--r--  131 xyz 19 May 11:05 mod.d.ts
.rw-r--r-- 2.9k xyz 19 May 11:05 mod.mjs
.rw-r--r-- 9.9k xyz 19 May 11:05 mod.mjs.map

packages/cli/dist:
.rw-r--r-- 23k xyz 19 May 11:05 main.mjs
.rw-r--r-- 43k xyz 19 May 11:05 main.mjs.map
drwxr-xr-x   - xyz 19 May 11:05 packages

yarn build
yarn run v1.22.19
$ npm-run-all --parallel build:*
$ microbundle --cwd packages/api --target web --format modern,cjs && cp -l packages/api/dist/api/src/mod.d.ts packages/api/dist/mod.d.ts
$ microbundle --cwd packages/cli --target node --format modern
Build "cli" to dist:
      6.28 kB: main.modern.js.gz
      5.57 kB: main.modern.js.br
Build "api" to dist:
      1.81 kB: mod.cjs.gz
       1.6 kB: mod.cjs.br
       1140 B: mod.modern.js.gz
        978 B: mod.modern.js.br
Done in 6.75s.

10:47:22 [I] ➜ exa -al packages/*/dist
packages/api/dist:
drwxr-xr-x    - xyz 19 May 10:47 api
drwxr-xr-x    - xyz 19 May 10:47 lib
.rw-r--r-- 5.5k xyz 19 May 10:47 mod.cjs
.rw-r--r--  12k xyz 19 May 10:47 mod.cjs.map
.rw-r--r--  131 xyz 19 May 10:47 mod.d.ts
.rw-r--r-- 3.0k xyz 19 May 10:47 mod.modern.js
.rw-r--r-- 9.9k xyz 19 May 10:47 mod.modern.js.map

packages/cli/dist:
.rw-r--r-- 23k xyz 19 May 10:47 main.modern.js
.rw-r--r-- 43k xyz 19 May 10:47 main.modern.js.map
drwxr-xr-x   - xyz 19 May 10:47 packages

───────┬───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
       │ File: packages/api/package.json
       │ Size: 276 B
───────┼───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   1   │ {
   2   │   "name": "api",
   3   │   "private": true,
   4   │   "description": "API to write tests running in the browser",
   5   │   "type": "module",
   6   │   "source": "src/mod.ts",
   7   │   "types": "dist/mod.d.ts",
   8   │   "main": "dist/mod.cjs",
   9   │   "esmodule": "dist/mod.mjs",
  10   │   "dependencies": {
  11   │     "emittery": "*"
  12   │   }
  13   │ }
───────┴───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
───────┬───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
       │ File: packages/cli/package.json
       │ Size: 647 B
───────┼───────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
   1   │ {
   2   │   "name": "cli",
   3   │   "private": true,
   4   │   "description": "CLI to run tests written with the API",
   5   │   "type": "module",
   6   │   "source": "src/main.ts",
   7   │   "main": "dist/main.cjs",
   8   │   "esmodule": "dist/main.mjs",
   9   │   "dependencies": {
  10   │     "@rollup/plugin-commonjs": "*",
  11   │     "@rollup/plugin-json": "*",
  12   │     "@rollup/plugin-node-resolve": "*",
  13   │     "@rollup/plugin-typescript": "*",
  14   │     "chalk": "*",
  15   │     "ci-info": "*",
  16   │     "emittery": "*",
  17   │     "express": "*",
  18   │     "figures": "*",
  19   │     "get-port": "*",
  20   │     "globby": "*",
  21   │     "matcher": "*",
  22   │     "ms": "*",
  23   │     "p-queue": "*",
  24   │     "playwright": "*",
  25   │     "rollup": "*",
  26   │     "supertap": "*",
  27   │     "yargs": "*"
  28   │   }
  29   │ }