Address BC 1.80 deprecation warnings

[bpholt]

BC 1.80 introduced two deprecation warnings that pop up in this project:

[warn] …/fs2-pgp/core/src/main/scala/com/dwolla/security/crypto/CryptoAlg.scala:179:51: method getKeyID in class PGPPublicKeyEncryptedData is deprecated
[warn]                   val recipientKeyId = Option(pbe.getKeyID).filterNot(_ == 0)
[warn]                                                   ^
[warn] …/fs2-pgp/core/src/main/scala/com/dwolla/security/crypto/CryptoAlg.scala:186:81: method getKeyID in class PGPPublicKeyEncryptedData is deprecated
[warn]                         Logger[F].trace(ex)(s"could not decrypt using key ${pbe.getKeyID}").as(None)
[warn]                                                                                 ^
[info] done compiling
[warn] two warnings found
[info] compiling 2 Scala sources to /Users/bholt/Developer/github/fs2-pgp/testkit/target/scala-2.13/classes ...
[warn] …/fs2-pgp/testkit/src/main/scala/com/dwolla/testutils/PgpArbitraries.scala:60:13: constructor JcaPGPKeyPair in class JcaPGPKeyPair is deprecated
[warn]             new JcaPGPKeyPair(PublicKeyAlgorithmTags.RSA_GENERAL, pair, now)
[warn]             ^
[info] done compiling
[warn] one warning found

We should migrate from using Long key IDs to using the new KeyIdentifier introduced in BC 1.80, or potentially migrate fully to using key fingerprints, which sounds like what BouncyCastle is planning to do long-term (see bcgit/bc-java #1752).

The change to JcaPGPKeyPair is less impactful. The constructor now takes a key version parameter, so we should be able to start setting that where it's available.