CI failures running Rust 1.48 and 1.49 on ubuntu-latest and windows-latest

[arik-so]

The Cargo manifest cannot be parsed due to a serde dependency with version 1.0.187.

Here's an example of CI failing: https://github.com/lightningdevkit/rust-lightning/actions/runs/5979401369/job/16223410901

[TheBlueMatt]

Reported upstream cause they seemed to indicate in the pr they didn't expect breakage, but I assume we may simply have to pin.

[TheBlueMatt]

serde fixed the MSRV change.

[arik-so]

Looks like now something similar has popped up with memchr https://github.com/lightningdevkit/rust-lightning/actions/runs/6002779089/job/16279839082

[jkczyz]

Looks like now something similar has popped up with memchr https://github.com/lightningdevkit/rust-lightning/actions/runs/6002779089/job/16279839082

Looks like #2537 doesn't fix this according to CI.

[TheBlueMatt]

Should be fixed.