fix: freeze time in logstash formatter test to prevent flaky failures

The test was comparing timestamps captured at different moments,
causing intermittent failures when a second boundary was crossed.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: jnunemaker

spec/httparty/logger/logstash_formatter_spec.rb

@@ -7,7 +7,8 @@
   let(:path) { 'http://my.domain.com/my_path' }
   let(:logger_double) { double('Logger') }
   let(:request_double) { double('Request', http_method: Net::HTTP::Get, path: "#{path}") }
-  let(:request_time) { Time.new.strftime("%Y-%m-%d %H:%M:%S %z") }
+  let(:frozen_time) { Time.new(2024, 1, 1, 12, 0, 0, "+00:00") }
+  let(:request_time) { frozen_time.strftime("%Y-%m-%d %H:%M:%S %z") }
   let(:log_message) do
     {
       '@timestamp' => request_time,
@@ -25,6 +26,7 @@
   subject { described_class.new(logger_double, severity) }
 
   before do
+    allow(Time).to receive(:now).and_return(frozen_time)
     expect(logger_double).to receive(:info).with(log_message)
   end