coverity: Our coverity job needs curl; install it

curl \
 --form token="$token" \
 --form email=holger@freyther.de --form file=@Osmocom.tgz \
 --form version=Version --form description=AutoUpload \
 https://scan.coverity.com/builds?project=Osmocom
./jenkins.sh: line 39: curl: command not found

Change-Id: Ibf4a40860fe6c8424a60672dc4758b9f17c532a3

ansible/roles/install-coverity/tasks/main.yml

@@ -1,4 +1,10 @@
 ---
+- name: install coverity-required debian packages
+  apt:
+    name: "{{ item }}"
+  with_items:
+    - curl
+
 - name: copy coverity installer
   copy:
     src: "{{ coverity_installer_file }}"