Migrate to pnpm

migrate_pnpm () {
  perl -pi \
    -e 's/          cache: yarn/      - run: corepack enable pnpm/;' \
    -e 's/- run: yarn$/- run: pnpm i/;' \
    -e 's/- run: yarn build/- run: pnpm build/;' \
    -e 's/\s+- run: yarn package\s//;' \
    .github/workflows/release.yaml

  perl -pi \
    -e "s/- action.yaml/- '*.yaml'/;" \
    -e 's/          cache: yarn/      - run: corepack enable pnpm/;' \
    -e 's/- run: yarn$/- run: pnpm i/;' \
    -e 's/\s+- run: yarn package\s//;' \
    -e 's/- run: yarn /- run: pnpm /;' \
    .github/workflows/ts.yaml

  perl -pi \
    -e 's/\s+"main": .+\s//;' \
    -e 's/\s+"build": .+\s//;' \
    -e 's/\s+"format-check": .+\s//;' \
    -e 's/"package": .+/"build": "ncc build --source-map --license licenses.txt src\/main.ts",/;' \
    -e 's/"\@tsconfig\/node16": .+/"\@tsconfig\/node20": "20.1.2",/;' \
    package.json

  perl -pi \
    -e 's/node16/node20/;' \
    tsconfig.json

  rm yarn.lock
  rm -fr node_modules
  pnpm i
}

create_migration_pnpm () {
  git fom
  git cob pnpm
  migrate_pnpm
  git add .
  git ci -m 'Migrate to pnpm'
  ghpc --body 'https://github.com/int128/typescript-action/issues/746'
}

Start with .github/workflows/release.yaml, .github/workflows/ts.yaml, package.json, and tsconfig.json, using the migration commands in the issue as a checklist. Update the workflows and package configuration for pnpm and Node 20, remove yarn.lock, and verify the resulting installation and build succeed with pnpm.