Bump default timeout to 2m

The current default of 10s is problematic when testing slower probes
from a browser. Cancellation will still work as a fallback,
including for older Prometheus servers that don't send the timeout
header, so there shouldn't be a big buildup of ongoing probes.

Fixes #259

Signed-off-by: Brian Brazil <[email protected]>

main.go

@@ -354,7 +354,7 @@ func getTimeout(r *http.Request, module config.Module, offset float64) (timeoutS
 		}
 	}
 	if timeoutSeconds == 0 {
-		timeoutSeconds = 10
+		timeoutSeconds = 120
 	}
 
 	var maxTimeoutSeconds = timeoutSeconds - offset