rebase: bump golang.org/x/crypto from 0.2.0 to 0.3.0

Bumps [golang.org/x/crypto](https://github.com/golang/crypto) from 0.2.0 to 0.3.0.
- [Release notes](https://github.com/golang/crypto/releases)
- [Commits](https://github.com/golang/crypto/compare/v0.2.0...v0.3.0)

---
updated-dependencies:
- dependency-name: golang.org/x/crypto
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

vendor/golang.org/x/crypto/ssh/common.go

@@ -10,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"math"
+	"strings"
 	"sync"
 
 	_ "crypto/sha1"
@@ -118,6 +119,20 @@ func algorithmsForKeyFormat(keyFormat string) []string {
 	}
 }
 
+// supportedPubKeyAuthAlgos specifies the supported client public key
+// authentication algorithms. Note that this doesn't include certificate types
+// since those use the underlying algorithm. This list is sent to the client if
+// it supports the server-sig-algs extension. Order is irrelevant.
+var supportedPubKeyAuthAlgos = []string{
+	KeyAlgoED25519,
+	KeyAlgoSKED25519, KeyAlgoSKECDSA256,
+	KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521,
+	KeyAlgoRSASHA256, KeyAlgoRSASHA512, KeyAlgoRSA,
+	KeyAlgoDSA,
+}
+
+var supportedPubKeyAuthAlgosList = strings.Join(supportedPubKeyAuthAlgos, ",")
+
 // unexpectedMessageError results when the SSH message that we received didn't
 // match what we wanted.
 func unexpectedMessageError(expected, got uint8) error {