Fix riemann-haproxy with Ruby 3.0+

Ruby 3.0 fully separated keyword arguments from positional arguments.
The `riemann-haproxy` tool has been broken with these versions of Ruby.

Use the new syntax to unbreak the tool on these versions of Ruby.

Author: smortex

lib/riemann/tools/haproxy.rb

@@ -44,7 +44,7 @@ def tick
       end
 
       def csv
-        CSV.parse(body.split('# ')[1], { headers: true })
+        CSV.parse(body.split('# ')[1], headers: true)
       end
 
       def body