fix: bump go toolchain to 1.24.6 (#19449)

Author: grobinson-grafana

go.mod

@@ -2,7 +2,7 @@ module github.com/grafana/loki/v3
 
 go 1.24.0
 
-toolchain go1.24.1
+toolchain go1.24.6
 
 require (
 	cloud.google.com/go/bigtable v1.40.1