Use standalone version of pnpm to fix electron-builder issues

Author: CommandMC

.github/actions/install-deps/action.yml

@@ -9,6 +9,7 @@ runs:
     - uses: pnpm/action-setup@v3
       with:
         version: 8
+        standalone: true
     - name: Install node-gyp
       run: pnpm add --global node-gyp
       shell: bash

README.md

@@ -207,15 +207,17 @@ Otherwise, download the file ending in .dmg from the [latest release](https://gi
 
 This part will walk you through setting up a development environment so you can build Heroic binaries yourself or make changes to the code.
 
-1. Make sure Git, NodeJS, and PNPM are installed
+1. Make sure Git, NodeJS, and PNPM are installed  
+   **NOTE**: Due to an issue with electron-builder, you'll need the standalone version of pnpm (`@pnpm/exe`) to build
+   packages
 2. Clone the repo and enter the cloned folder, for example with these commands:
 
    ```bash
    git clone https://github.com/Heroic-Games-Launcher/HeroicGamesLauncher.git --recurse-submodules
    cd HeroicGamesLauncher
    ```
 
-3. Make sure all dependencies are installed by running `pnpm`
+3. Make sure all dependencies are installed by running `pnpm install`
 
 ### Building Heroic Binaries