build: update yamllint config (#7743)

This commit updates the `.yamllint` configuration file
by forbid the usage of `braces` and `brackets` in the
template file which coincidentally was introduced in the
commit 249ad821ec.

These changes aim to enhance the overall template syntax
quality and maintain a consistent style throughout the
Nuclei template files.

Signed-off-by: Dwi Siswanto <me@dw1.io>

.yamllint

@@ -18,4 +18,8 @@ rules:
     ignore-shebangs: true
     min-spaces-from-content: 1
   empty-lines:
-    max: 5
+    max: 5
+  braces:
+    forbid: true
+  brackets:
+    forbid: true