fix(ci): remove pnpm version override conflicting with packageManager

pnpm/action-setup@v4 reads packageManager from package.json automatically.
Specifying `version: latest` alongside `packageManager: pnpm@10.0.0` causes
ERR_PNPM_BAD_PM_VERSION. Remove the explicit version so it uses package.json.

Author: pikespeak

.github/workflows/ci.yml

@@ -12,7 +12,6 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
-        with: { version: latest }
       - uses: actions/setup-node@v4
         with: { node-version: "lts/*", cache: "pnpm" }
       - run: pnpm install --frozen-lockfile

.github/workflows/publish.yml

@@ -13,7 +13,6 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
-        with: { version: latest }
       - uses: actions/setup-node@v4
         with:
           node-version: "lts/*"