Restore TAURI_SIGNING_PRIVATE_KEY environment variable. (#5094)

Author: trojanfoe

.github/workflows/build-nym-vpn-app-windows.yml

@@ -290,6 +290,8 @@ jobs:
         working-directory: nym-vpn-app/src-tauri
         shell: bash
         env:
+          TAURI_SIGNING_PRIVATE_KEY: ${{ secrets.TAURI_PRIVATE_KEY }}
+          TAURI_SIGNING_PRIVATE_KEY_PASSWORD: ${{ secrets.TAURI_KEY_PASSWORD }}
           SSL_COM_USERNAME: ${{ secrets.SSL_COM_USERNAME }}
           SSL_COM_PASSWORD: ${{ secrets.SSL_COM_PASSWORD }}
           SSL_COM_TOTP_SECRET: ${{ secrets.SSL_COM_TOTP_SECRET }}