Make sure DelayType function gets consistent values of n

Without this change DelayType function gets n either from
0,1,2,... or from 1,2,3,... depending on the value of Attempts
config value.

This change unifies the behaviour and makes n always take values from
1,2,3,...

Fixes #124

Signed-off-by: Piotr Jastrzebski <[email protected]>

Author: haaawk

retry.go

@@ -202,7 +202,7 @@ func DoWithData[T any](retryableFunc RetryableFuncWithData[T], opts ...Option) (
 		if n == config.attempts-1 {
 			break
 		}
-
+		n++
 		select {
 		case <-config.timer.After(delay(config, n, err)):
 		case <-config.context.Done():
@@ -213,7 +213,6 @@ func DoWithData[T any](retryableFunc RetryableFuncWithData[T], opts ...Option) (
 			return emptyT, append(errorLog, config.context.Err())
 		}
 
-		n++
 		shouldRetry = shouldRetry && n < config.attempts
 	}