README.md(s): use img.shields.io crate version badges

crypto_secretbox/README.md

@@ -45,7 +45,7 @@ dual licensed as above, without any additional terms or conditions.
 
 [//]: # (badges)
 
-[crate-image]: https://buildstats.info/crate/crypto_secretbox
+[crate-image]: https://img.shields.io/crates/v/crypto_secretbox
 [crate-link]: https://crates.io/crates/crypto_secretbox
 [docs-image]: https://docs.rs/crypto_secretbox/badge.svg
 [docs-link]: https://docs.rs/crypto_secretbox/