macOS: add Knot 3.2

Adds a second macOS job that builds the resolver with libknot 3.2 (also keeps 3.1 right now)

.github/workflows/macOS.yaml

@@ -6,6 +6,9 @@ jobs:
   build-test:
     name: Build & unit tests & sanity check
     runs-on: macOS-latest
+    strategy:
+      matrix:
+        knot-version: ['3.1', '3.2']
 
     steps:
       - name: Checkout resolver code
@@ -19,7 +22,7 @@ jobs:
 
       - name: Install libknot from sources
         env:
-          KNOT_DNS_VERSION: '3.1'
+          KNOT_DNS_VERSION: ${{ matrix.knot-version }}
         run: |
           git clone -b ${KNOT_DNS_VERSION} https://gitlab.nic.cz/knot/knot-dns.git
           cd knot-dns