retry.Retryable(): don't re-try context.DeadlineExceeded

[Al2Klimov]

It is considered temporary and timeout, but we don't want to retry on it.

[oxzi]

Context for this PR is provided in #23 (comment).

[yhabteab]

Are you sure this won't break something? There is already a special handling for ctx and network I/O errors here.

icinga-go-library/retry/retry.go

Lines 72 to 77 in 2eac186

	// Retryable function may have exited prematurely due to context errors.
	// We explicitly check the context error here, as the error returned by the retryable function can pass the
	// error.Is() checks even though it is not a real context error, e.g.
	// https://cs.opensource.google/go/go/+/refs/tags/go1.22.2:src/net/net.go;l=422
	// https://cs.opensource.google/go/go/+/refs/tags/go1.22.2:src/net/net.go;l=601
	if errors.Is(ctx.Err(), context.DeadlineExceeded) || errors.Is(ctx.Err(), context.Canceled) {

(｡･_･｡)

[yhabteab]

This breaks the retry logic as stated in #67 (comment) , so it is not going to happen!