fix: Add Tauri signing environment variables to release workflow

- Add TAURI_SIGNING_PRIVATE_KEY to env
- Add TAURI_SIGNING_PRIVATE_KEY_PASSWORD to env
- Fixes 'no private key found' error during GitHub Actions build

Author: KwaminaWhyte

.github/workflows/release.yml

@@ -70,6 +70,8 @@ jobs:
         uses: tauri-apps/tauri-action@v0
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TAURI_SIGNING_PRIVATE_KEY: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY }}
+          TAURI_SIGNING_PRIVATE_KEY_PASSWORD: ${{ secrets.TAURI_SIGNING_PRIVATE_KEY_PASSWORD }}
         with:
           tagName: ${{ github.ref_name }}
           releaseName: "DB-Hive ${{ github.ref_name }}"