Upgrade electron-builder to fix pnpm issues

electron-builder 26.0.13 had issues with macOS code signing when using
  pnpm, causing it to fall back to ad-hoc signatures. This was due to
  passing identity hash instead of name to osx-sign, which prevented
  TeamID extraction.

  Key fixes in 26.3.6:
  - PR #8908: osx-sign now receives identity name instead of hash
  - PR #9392: Fix pnpm hoisted mode virtual path handling
  - PR #9401: Filesystem verification for hoisted mode
  - Issue #9366: Universal build fixes for pnpm monorepos

  Changes:
  - Upgrade electron-builder from 26.0.13 to 26.3.6
  - Add electron-builder-squirrel-windows 26.3.6 (peer dependency)
  - Add squirrel-windows to Renovate config with grouping rule
  - Remove CSC_NAME workaround (no longer needed with identity fix)

  References:
  - https://github.com/electron-userland/electron-builder/issues/7995
  - https://github.com/electron-userland/electron-builder/pull/8908

.github/workflows/build-desktop.yml

@@ -1499,7 +1499,6 @@ jobs:
           APP_STORE_CONNECT_AUTH_KEY: 6TV9MKN3GP
           APP_STORE_CONNECT_AUTH_KEY_PATH: ~/private_keys/AuthKey_6TV9MKN3GP.p8
           CSC_FOR_PULL_REQUEST: true
-          CSC_NAME: "8bit Solutions LLC"
         run: pnpm run pack:mac
 
       - name: Upload .zip artifact
@@ -1788,7 +1787,6 @@ jobs:
           APP_STORE_CONNECT_AUTH_KEY: 6TV9MKN3GP
           APP_STORE_CONNECT_AUTH_KEY_PATH: ~/private_keys/AuthKey_6TV9MKN3GP.p8
           CSC_FOR_PULL_REQUEST: true
-          CSC_NAME: "Bitwarden Inc"
         run: pnpm run pack:mac:mas
 
       - name: Create MacOS App Store build number artifact