tests: Install libelf-dev as a dependency to build bpftool

Signed-off-by: Gwendolyn <[email protected]>

Author: gwenya

.github/workflows/tests.yml

@@ -270,6 +270,7 @@ jobs:
             libcap-dev \
             libdbus-1-dev \
             libcowsql-dev \
+            libelf-dev \
             liblxc-dev \
             libseccomp-dev \
             libselinux-dev \