fix: rename countDistinct to countdistinct in allowed functions

Author: catalyst17

internal/common/utils.go

@@ -25,7 +25,7 @@ func SliceToChunks[T any](values []T, chunkSize int) [][]T {
 var allowedFunctions = map[string]struct{}{
 	"sum":                  {},
 	"count":                {},
-	"countDistinct":        {},
+	"countdistinct":        {},
 	"avg":                  {},
 	"max":                  {},
 	"min":                  {},