dev-ruby/async: remove unused patch(es)

Signed-off-by: Michael Mair-Keimberger <mm1ke@gentoo.org>

dev-ruby/async/files/async-1.31.0-improve-robustness-test.patch

@@ -1,49 +0,0 @@
-https://github.com/socketry/async/commit/8f590415c08943372e0227f01d3c32e92dbcbed0
-https://github.com/socketry/async/issues/218
-
-From 8f590415c08943372e0227f01d3c32e92dbcbed0 Mon Sep 17 00:00:00 2001
-From: Samuel Williams <samuel.williams@oriontransfer.co.nz>
-Date: Sun, 12 Mar 2023 20:33:48 +1300
-Subject: [PATCH] Improve robustness of test, fixes #218.
-
---- a/spec/async/semaphore_spec.rb
-+++ b/spec/async/semaphore_spec.rb
-@@ -62,7 +62,7 @@
- 			3.times.map do |i|
- 				semaphore.async do |task|
- 					order << i
--					task.sleep(0.1)
-+					task.yield
- 					order << i
- 				end
- 			end.collect(&:result)
-@@ -72,17 +72,22 @@
- 		
- 		it 'allows tasks to execute concurrently' do
- 			semaphore = Async::Semaphore.new(3)
--			order = []
-+			concurrency = 0
-+			latch = Async::Condition.new
- 			
- 			3.times.map do |i|
- 				semaphore.async do |task|
--					order << i
--					task.sleep(0.1)
--					order << i
-+					concurrency += 1
-+					
-+					if concurrency == 3
-+						latch.signal
-+					else
-+						latch.wait
-+					end
- 				end
--			end.collect(&:result)
-+			end.each(&:wait)
- 			
--			expect(order).to be == [0, 1, 2, 0, 1, 2]
-+			expect(concurrency).to be == 3
- 		end
- 	end
- 	
-