Update 2022-06-16-sparse-registry-testing.md

Update links

Author: arlosi

posts/2022-06-16-sparse-registry-testing.md

@@ -64,6 +64,6 @@ Thank you to everyone involved!
 
 [rfc]: https://rust-lang.github.io/rfcs/2789-sparse-index.html
 [sparse-registry]: https://doc.rust-lang.org/nightly/cargo/reference/unstable.html#sparse-registry
-[internals]: https://internals.rust-lang.org/t/xxxxxxxxxxxxxxxxxxxxxxxxx
+[internals]: https://internals.rust-lang.org/t/call-for-testing-cargo-sparse-registry/16862
 [tracking-issue]: https://github.com/rust-lang/cargo/issues/9069
-[cargo]: https://github.com/rust-lang/cargo
+[cargo]: https://github.com/rust-lang/cargo/issues