ci: add build testing against named-data PPA

Also, skip examples in code-coverage builds

Change-Id: I11a728eb3f469e0838217fada5184833ba191198
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a9f36bb..8cbb310 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,3 +10,7 @@
     uses: named-data/actions/.github/workflows/jenkins-script-ubuntu.yml@v1
   macOS:
     uses: named-data/actions/.github/workflows/jenkins-script-macos.yml@v1
+  PPA:
+    uses: named-data/actions/.github/workflows/ppa.yml@v1
+    with:
+      extra-deps: libboost-iostreams-dev