Bump libsecp256k1 from 0.6.0 to 0.7.0 (#296)

* Bump libsecp256k1 from 0.6.0 to 0.7.0

Bumps [libsecp256k1](https://github.com/paritytech/libsecp256k1) from 0.6.0 to 0.7.0.
- [Release notes](https://github.com/paritytech/libsecp256k1/releases)
- [Changelog](https://github.com/paritytech/libsecp256k1/blob/master/CHANGELOG.md)
- [Commits](https://github.com/paritytech/libsecp256k1/commits)

---
updated-dependencies:
- dependency-name: libsecp256k1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

* update sec advisories

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: adoerr <[email protected]>

Author: dependabot[bot]

frame/beefy-mmr/Cargo.toml

@@ -9,7 +9,7 @@ description = "BEEFY + MMR runtime utilities"
 [dependencies]
 hex = { version = "0.4", optional = true }
 codec = { version = "2.0.0", package = "parity-scale-codec", default-features = false, features = ["derive"] }
-libsecp256k1 = { version = "0.6.0", default-features = false }
+libsecp256k1 = { version = "0.7.0", default-features = false }
 log = { version = "0.4.13", default-features = false }
 scale-info = { version = "1.0", default-features = false, features = ["derive"] }
 serde = { version = "1.0.130", optional = true }