CI: use system docopt-cpp

Change-Id: Ib246d39f975c00bc6489f683f1f21f34cc808201
Depend-on: https://gerrit.cesnet.cz/c/CzechLight/dependencies/+/6009
diff --git a/ci/pre.yaml b/ci/pre.yaml
index 5d3bfe9..ef2b203 100644
--- a/ci/pre.yaml
+++ b/ci/pre.yaml
@@ -11,3 +11,9 @@
         name: pam-devel
         state: present
       become: true
+
+    - name: install docopt-cpp
+      package:
+        name: docopt-cpp-devel
+        state: present
+      become: true