migrate to pnpm (#609)

* migrate to `pnpm`

* rename `simple-project` fixture packages to remove socket security errors

* add pnpm `dedupe` options

* update release-pr workflow

* update

* update snashots

* tweaks

* tweak

* tweak

* fix missing ci-setup

* tweak

* tweak deps

* update pnpm

* ok, Socket, let's rename them

* update snapshots

* rename again

* fmt

---------

Co-authored-by: Mateusz Burzyński <mateuszburzynski@gmail.com>

.github/actions/ci-setup/action.yml

@@ -1,14 +1,17 @@
 name: Setup CI
+description: Setup CI
 
 runs:
   using: composite
   steps:
-    - name: Setup Node.js
-      uses: actions/setup-node@53b83947a5a98c8d113130e565377fae1a50d02f # v6.3.0
+    - name: Set up pnpm
+      uses: pnpm/action-setup@8912a9102ac27614460f54aedde9e1e7f9aec20d # v6.0.5
+
+    - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
       with:
         node-version-file: ".node-version"
-        cache: yarn
+        cache: pnpm
 
     - name: Install dependencies
       shell: bash
-      run: yarn install --frozen-lockfile
+      run: pnpm install --frozen-lockfile