Release v0.6.0

[conradoplg]

Check version number is correct:

• [x] Frost core version number
• [x] Frost ed25519 version number
• [x] Frost ed448 version number
• [x] Frost p256 version number
• [x] Frost rerandomized version number
• [x] Frost ristretto255 version number
• [x] Frost secp256k1 version number

Update changelog:

• [x] Check content
• [x] Move version in changelog to Released
• [x] Create a new version in “unreleased” in changelog

Update the version number for frost-core in the Ciphersuite crates, e.g. in frost-core = { path = "../frost-core", version = "0.4.0", features = ["test-impl"] }:

• [x] Frost ed25519
• [x] Frost ed448
• [x] Frost p256
• [x] Frost ristretto255
• [x] Frost secp256k1
• [x] Frost rerandomized

[conradoplg]

Done!