update minimum Go version requirement to 1.23 in README.md (#747)

Author: shogo82148

README.md

@@ -1,7 +1,7 @@
 fsnotify is a Go library to provide cross-platform filesystem notifications on
 Windows, Linux, macOS, BSD, and illumos.
 
-Go 1.17 or newer is required; the full documentation is at
+Go 1.23 or newer is required; the full documentation is at
 https://pkg.go.dev/github.com/fsnotify/fsnotify
 
 ---