build: make go1.23 the minimum go version

This is necessary now that golang.org/x/crypto is only allowing the
last two versions of Go.

See: https://go.googlesource.com/crypto/+/89ff08d67c4d79f9ac619aaf1f7388888798651f

lib/file/mkdir.go

@@ -0,0 +1,8 @@
+package file
+
+import "os"
+
+// MkdirAll now just calls os.MkdirAll
+func MkdirAll(path string, perm os.FileMode) error {
+	return os.MkdirAll(path, perm)
+}