Fix yaml syntax in csvfile_lookup example (#81221)

Testing this example gives a parse error.
The correct syntax needs a colon for assignment, not equal sign

lib/ansible/plugins/lookup/csvfile.py

@@ -57,7 +57,7 @@ EXAMPLES = """
     neighbor_as: "{{ csvline[5] }}"
     neigh_int_ip: "{{ csvline[6] }}"
   vars:
-    csvline = "{{ lookup('ansible.builtin.csvfile', bgp_neighbor_ip, file='bgp_neighbors.csv', delimiter=',') }}"
+    csvline: "{{ lookup('ansible.builtin.csvfile', bgp_neighbor_ip, file='bgp_neighbors.csv', delimiter=',') }}"
   delegate_to: localhost
 """