Pin GitHub Actions and add runner hardening (#5628)

# Description of Changes

<!--
Please provide a summary of the changes, including:

- What was changed
- Why the change was made
- Any challenges encountered

Closes #(issue_number)
-->

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

.github/workflows/multiOSReleases.yml

@@ -130,7 +130,7 @@ jobs:
 
       - name: Setup Node.js
         if: matrix.variant.build_frontend == true
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 22
           cache: "npm"
@@ -185,14 +185,14 @@ jobs:
           sudo apt-get install -y libgtk-3-dev libwebkit2gtk-4.0-dev libwebkit2gtk-4.1-dev libappindicator3-dev librsvg2-dev patchelf libjavascriptcoregtk-4.0-dev libsoup2.4-dev libjavascriptcoregtk-4.1-dev libsoup-3.0-dev
 
       - name: Setup Node.js
-        uses: actions/setup-node@v4
+        uses: actions/setup-node@49933ea5288caeca8642d1e84afbd3f7d6820020 # v4.4.0
         with:
           node-version: 22
           cache: "npm"
           cache-dependency-path: frontend/package-lock.json
 
       - name: Setup Rust
-        uses: dtolnay/rust-toolchain@stable
+        uses: dtolnay/rust-toolchain@4be9e76fd7c4901c61fb841f559994984270fce7 # stable
         with:
           toolchain: stable
           targets: ${{ (matrix.platform == 'macos-15' || matrix.platform == 'macos-15-intel') && 'aarch64-apple-darwin,x86_64-apple-darwin' || '' }}
@@ -291,7 +291,7 @@ jobs:
       - name: Setup DigiCert KeyLocker
         id: digicert-setup
         if: ${{ matrix.platform == 'windows-latest' && env.SM_API_KEY != '' && (github.event_name == 'release' || github.ref == 'refs/heads/V2-master') }}
-        uses: digicert/ssm-code-signing@v1.1.0
+        uses: digicert/ssm-code-signing@9476ceec3ea1c63298d4403b983e1ccf2556ff4c # v1.1.0
         env:
           SM_API_KEY: ${{ secrets.SM_API_KEY }}
           SM_CLIENT_CERT_FILE_B64: ${{ secrets.SM_CLIENT_CERT_FILE_B64 }}
@@ -399,7 +399,7 @@ jobs:
           echo "Certificate imported successfully."
 
       - name: Build Tauri app
-        uses: tauri-apps/tauri-action@v0
+        uses: tauri-apps/tauri-action@51a9f1156b33df106d827c3a78f8f894946c5faa # v0.5.25
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           APPLE_CERTIFICATE: ${{ secrets.APPLE_CERTIFICATE }}