`libsecp256k1` v0.2.0 was just released.
Update the vendored code using
`./vendor-libsecp.sh depend 0_8_0 21ffe4b`
```
git show 21ffe4b
commit 21ffe4b22a9683cf24ae0763359e401d1284cc7a (tag: v0.2.0)
Merge: 8c949f5 e025ccd
Author: Pieter Wuille <pieter@wuille.net>
Date: Mon Dec 12 17:00:52 2022 -0500
Merge bitcoin-core/secp256k1#1055: Prepare initial release
e025ccdf7473702a76bb13d763dc096548ffefba release: prepare for initial release 0.2.0 (Jonas Nick)
6d1784a2e2c1c5a8d89ffb08a7f76fa15e84fff5 build: add missing files to EXTRA_DIST (Jonas Nick)
13bf1b6b324f2ed1c1fb4c8d17a4febd3556839e changelog: make order of change types match keepachangelog.com (Jonas Nick)
b1f992a552785395d2e60b10862626fd11f66f84 doc: improve release process (Jonas Nick)
ad39e2dc417f85c1577a6a6a9c519f5c60453def build: change package version to 0.1.0-dev (Jonas Nick)
90618e9263ebc2a0d73d487d6d94fd3af96b973c doc: move CHANGELOG from doc/ to root directory (Jonas Nick)
Pull request description:
Based on #964
ACKs for top commit:
sipa:
ACK e025ccdf7473702a76bb13d763dc096548ffefba
Tree-SHA512: b9ab71d7362537d383a32b5e321ef44069f00e3e92340375bcd662267bc5a60c2bad60222998e6602cfac24ad65efb23d772eac37c86065036b90ef090b54c49
```
Requires a new version of `secp256k1-sys`, use v0.8.0
- Update the `secp256k1-sys` manifest (including links field)
- Update symbols to use 0_8_0
- Add a changelog entry
- depend on the new version in `secp256k1`
Which in turn requires a new version of `secp256k1`, use v0.26.0
Recently we found and fixed an unsoundness issue in the
`preallocated_gen_new` function. As we have yet to release 0.25.0 we can
just update the changelog to reflect the newly merged fix.
We just applied a hot fix to the 0.23.0 released code to fix the
features enabled in `rand` when our "rand-std" feature is enabled. This
requires a bump of the patch version for release.
Bump the version and add a changelog entry.
`Default` was pointless, so it was replaced with internal
`from_raw_parts` method which also checks the length.
This commit also documents changes to `SerializedSignature`.
Closes#454