chore: bump Go to 1.21 (#42)

tmzane · web-flow · commit 38a4f9ee9f84 · 2024-05-10T00:38:20.000+03:00
diff --git a/go.mod b/go.mod
@@ -1,6 +1,6 @@
 module go-simpler.org/sloglint
 
-go 1.20
+go 1.21
 
 require (
 	github.com/ettle/strcase v0.2.0
