flaky TTL test

[marten-seemann]

=== RUN   TestTTLs/IPv4
2024/11/09 16:50:03 dropping proxied packet (20 bytes) that can't be proxied: connect-ip: datagram TTL too small: 1
2024/11/09 16:50:03 handling stream failed: Application error 0x100 (local)
2024/11/09 16:50:03 writing to stream failed: use of closed network connection
=== RUN   TestTTLs/IPv6
2024/11/09 16:50:03 handling stream failed: INTERNAL_ERROR (local): read udp 127.0.0.1:49375: raw-read udp4 127.0.0.1:49375: use of closed network connection
2024/11/09 16:50:03 writing to stream failed: use of closed network connection
    proxy_test.go:193: 
        	Error Trace:	/Users/runner/work/connect-ip-go/connect-ip-go/proxy_test.go:193
        	Error:      	Received unexpected error:
        	            	context deadline exceeded
        	Test:       	TestTTLs/IPv6
2024/11/09 16:50:03 handling stream failed: INTERNAL_ERROR (local): read udp [127](https://github.com/quic-go/connect-ip-go/actions/runs/11757891428/job/32755664928?pr=25#step:6:128).0.0.1:62598: raw-read udp4 127.0.0.1:62598: use of closed network connection
2024/11/09 16:50:03 writing to stream failed: use of closed network connection
2024/11/09 16:50:03 handling stream failed: Application error 0x100 (local)
2024/11/09 16:50:03 writing to stream failed: use of closed network connection
--- FAIL: TestTTLs (0.04s)
    --- PASS: TestTTLs/IPv4 (0.02s)
    --- FAIL: TestTTLs/IPv6 (0.03s)