Bump version to 0.23.2

[vorot93]

No description provided.

[apoelstra]

ACK 141f2d1

[tcharding]

Tagging doesn't seemed to have worked on this release either @apoelstra

$ git fetch --all --tags; git tag | grep secp256k1-0.23
Fetching origin
Fetching upstream
secp256k1-0.23.0
secp256k1-0.23.1

[apoelstra]

Ah, I see, git push --tags on this repo just sends stuff to my personal fork.

I will remember to type git push origin --tags in the future.

Should be good now.

[tcharding]

If your brain works anything like mine you'll forget at least one more time, in these cases I add a shell alias, somehow my brain remembers to use it, I'm not sure why.