Switch element-desktop from yarn classic to pnpm (#2843)

.github/workflows/build_test.yaml

@@ -40,13 +40,14 @@ jobs:
               with:
                   repository: ${{ github.repository == 'element-hq/element-web-pro' && 'element-hq/element-desktop' || github.repository }}
 
+            - uses: pnpm/action-setup@41ff72655975bd51cab0327fa583b6e92b6d3061 # v4
             - uses: actions/setup-node@6044e13b5dc448c55e2357c09f80417699197238 # v6
               with:
                   node-version-file: .node-version
-                  cache: "yarn"
+                  cache: "pnpm"
 
             - name: Install Deps
-              run: "yarn install --frozen-lockfile"
+              run: "pnpm install --frozen-lockfile"
 
             - uses: actions/download-artifact@37930b1c2abaa49bbe596cd826c3c89aef350131 # v7
               with:
@@ -80,7 +81,7 @@ jobs:
               uses: coactions/setup-xvfb@6b00cf1889f4e1d5a48635647013c0508128ee1a
               timeout-minutes: 20
               with:
-                  run: yarn test --project=${{ inputs.project }} ${{ runner.os != 'Linux' && '--ignore-snapshots' || '' }} ${{ inputs.blob_report == false && '--reporter=html' || '' }} ${{ inputs.args }}
+                  run: pnpm test --project=${{ inputs.project }} ${{ runner.os != 'Linux' && '--ignore-snapshots' || '' }} ${{ inputs.blob_report == false && '--reporter=html' || '' }} ${{ inputs.args }}
               env:
                   ELEMENT_DESKTOP_EXECUTABLE: ${{ steps.executable.outputs.path }}