[StepSecurity] Apply security best practices

Added a step to harden the runner by auditing outbound calls in multiple jobs.

Author: MH0386

.github/workflows/ci.yml

@@ -18,6 +18,10 @@ jobs:
     environment:
       name: code_quality
     steps:
+      - name: Harden the runner (Audit all outbound calls)
+        uses: step-security/harden-runner@95d9a5deda9de15063e7595e9719c11c38c90ae2 # v2.13.2
+        with:
+          egress-policy: audit
       - name: Checkout repository
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - name: Install Nix
@@ -36,6 +40,10 @@ jobs:
     environment:
       name: code_quality
     steps:
+      - name: Harden the runner (Audit all outbound calls)
+        uses: step-security/harden-runner@95d9a5deda9de15063e7595e9719c11c38c90ae2 # v2.13.2
+        with:
+          egress-policy: audit
       - name: Checkout repository
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:
@@ -63,6 +71,10 @@ jobs:
     environment:
       name: build
     steps:
+      - name: Harden the runner (Audit all outbound calls)
+        uses: step-security/harden-runner@95d9a5deda9de15063e7595e9719c11c38c90ae2 # v2.13.2
+        with:
+          egress-policy: audit
       - name: Checkout repository
         uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
       - name: Install Nix
@@ -97,6 +109,10 @@ jobs:
       url: ${{ steps.deployment.outputs.page_url }}
     if: github.event_name != 'pull_request'
     steps:
+      - name: Harden the runner (Audit all outbound calls)
+        uses: step-security/harden-runner@95d9a5deda9de15063e7595e9719c11c38c90ae2 # v2.13.2
+        with:
+          egress-policy: audit
       - name: Deploy to GitHub Pages
         id: deployment
         uses: actions/deploy-pages@d6db90164ac5ed86f2b6aed7e0febac5b3c0c03e # v4.0.5