CI: depend on libjson-c-dev

This is a dependency of the newly imported sscregistrygen.

Signed-off-by: Richard Acayan <mailingradian@gmail.com>

.github/workflows/build.yaml

@@ -21,7 +21,7 @@ jobs:
       - name: Dependencies
         run: |
           sudo apt update
-          sudo apt install -y meson ninja-build
+          sudo apt install -y meson ninja-build libjson-c-dev
 
       - name: build
         run: |