datasource/http: don't error on 2xx code

When a server returns a code that is not 200, we error in the current
state.

This is not conformant to the HTTP norm, as anything in the 2xx range is
considered a success, so the datasource should not error in this case.

Therefore, this commit fixes the condition in which we report an error,
so that anything in the 2xx range is now considered a success by the
datasource.

datasource/http/data.go

@@ -125,7 +125,7 @@ func (d *Datasource) Execute() (cty.Value, error) {
 
 	defer resp.Body.Close()
 
-	if resp.StatusCode != 200 {
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
 		return cty.NullVal(cty.EmptyObject), fmt.Errorf("HTTP request error. Response code: %d", resp.StatusCode)
 	}