Remove UPX from macOS build process

Updated the GitHub Actions workflow to exclude UPX installation and
usage on macOS. This change addresses compatibility issues with UPX
on macOS, ensuring smoother build processes for macOS environments.

More info: upx/upx#612

.github/workflows/build-binaries.yml

@@ -41,7 +41,7 @@ jobs:
 
       - name: Install dependencies (macOS)
         if: runner.os == 'macOS'
-        run: brew install upx cargo-c jemalloc
+        run: brew install cargo-c jemalloc
 
       - name: Set up Go
         uses: actions/setup-go@v5
@@ -51,7 +51,9 @@ jobs:
       - name: Build Juno
         run: |
           make juno
-          upx build/juno
+          if [[ "${{ runner.os }}" != "macOS" ]]; then
+            upx build/juno
+          fi
           mv build/juno ${{ env.ARTIFACT_NAME }}
 
       - name: Generate Checksum