ci: use the build args from the dotenv file

.github/workflows/test-tools.yml

@@ -32,15 +32,9 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
-      - name: Load .env file and set build-args
-        id: load-env
-        run: |
-          build_args=""
-          while read -r line; do
-            key=$(echo "$line" | cut -d '=' -f 1)
-            value=$(echo "$line" | cut -d '=' -f 2)
-            echo "$key=$value" >> build-args.txt
-          done < .env
+      - name: Load .env file
+        id: dotenv
+        uses: xom9ikk/dotenv@v2
 
       - name: Build container
         uses: docker/build-push-action@v6
@@ -50,8 +44,7 @@ jobs:
           cache-from: type=gha
           cache-to: type=gha,mode=max
           tags: theredguild/container-sec-tools:latest
-          build-args: |
-            $(cat build-args.txt)
+          build-args: ${{ steps.dotenv.outputs.vars }}
 
       - name: Check disk space
         run: df -h