bug: use URI.open instead of Kernel#open (Kernel#open fails in ruby 3.0)

Fixes #20

Author: benprew

Diff for: check_haproxy.rb

@@ -130,7 +130,7 @@ def haproxy_response(options)
   end
 
   begin
-    return open(options.url, open_options(options))
+    return URI.open(options.url, **open_options(options))
   rescue OpenURI::HTTPError => e
     puts "ERROR: #{e.message}"
     options.http_error_critical ? exit(CRITICAL) : exit(UNKNOWN)

Diff for: test/test_check_haproxy.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 NUM_TESTS=$(find test/haproxy/ -type f -name '*.csv' |wc -l|awk '{print $1}')
-echo "1..$(($NUM_TESTS + 2))" # this sucks, you have to add test count manually
+echo "1..$(($NUM_TESTS + 3))" # this sucks, you have to add test count manually
 I=1
 for f in test/haproxy/*.csv; do
     OUTPUT_FILE=$(mktemp)
@@ -36,3 +36,6 @@ do_test 'warn limit' \
 
 do_test 'crit limit' \
         "./check_haproxy.rb -u test/haproxy/fedoraproject_org.csv -w 1 -c2 -p fedmsg-raw-zmq-outbound-backend |grep 'CRIT.*too many sessions' > /dev/null"
+
+do_test 'live url' \
+        "./check_haproxy.rb -u 'http://demo.1wt.eu/' >/dev/null"