[Security] Bump sshpk from 1.11.0 to 1.15.1

Bumps [sshpk](https://github.com/joyent/node-sshpk) from 1.11.0 to 1.15.1. **This update includes security fixes.**
- [Release notes](https://github.com/joyent/node-sshpk/releases)
- [Commits](TritonDataCenter/node-sshpk@v1.11.0...v1.15.1)

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

yarn.lock

@@ -3392,12 +3392,6 @@ isstream@~0.1.2:
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/isstream/-/isstream-0.1.2.tgz#47e63f7af55afa6f92e1500e690eb8b8529c099a"
 
-jodid25519@^1.0.0:
-  version "1.0.2"
-  resolved "https://registry.yarnpkg.com/jodid25519/-/jodid25519-1.0.2.tgz#06d4912255093419477d425633606e0e90782967"
-  dependencies:
-    jsbn "~0.1.0"
-
 jquery@>=1.11, jquery@>=1.14.0, jquery@^3.2:
   version "3.2.1"
   resolved "https://registry.yarnpkg.com/jquery/-/jquery-3.2.1.tgz#5c4d9de652af6cd0a770154a631bba12b015c787"
@@ -5495,7 +5489,7 @@ safe-buffer@^5.1.1, safe-buffer@^5.1.2:
   version "5.1.2"
   resolved "https://registry.yarnpkg.com/safe-buffer/-/safe-buffer-5.1.2.tgz#991ec69d296e0313747d59bdfd2b745c35f8828d"
 
-"safer-buffer@>= 2.1.2 < 3":
+"safer-buffer@>= 2.1.2 < 3", safer-buffer@^2.0.2:
   version "2.1.2"
   resolved "https://registry.yarnpkg.com/safer-buffer/-/safer-buffer-2.1.2.tgz#44fa161b0187b9549dd84bb91802f9bd8385cd6a"
 
@@ -5855,18 +5849,17 @@ sprintf-js@~1.0.2:
   resolved "https://registry.yarnpkg.com/sprintf-js/-/sprintf-js-1.0.3.tgz#04e6926f662895354f3dd015203633b857297e2c"
 
 sshpk@^1.7.0:
-  version "1.11.0"
-  resolved "https://registry.yarnpkg.com/sshpk/-/sshpk-1.11.0.tgz#2d8d5ebb4a6fab28ffba37fa62a90f4a3ea59d77"
+  version "1.15.1"
+  resolved "https://registry.yarnpkg.com/sshpk/-/sshpk-1.15.1.tgz#b79a089a732e346c6e0714830f36285cd38191a2"
   dependencies:
     asn1 "~0.2.3"
     assert-plus "^1.0.0"
-    dashdash "^1.12.0"
-    getpass "^0.1.1"
-  optionalDependencies:
     bcrypt-pbkdf "^1.0.0"
+    dashdash "^1.12.0"
     ecc-jsbn "~0.1.1"
-    jodid25519 "^1.0.0"
+    getpass "^0.1.1"
     jsbn "~0.1.0"
+    safer-buffer "^2.0.2"
     tweetnacl "~0.14.0"
 
 ssri@^5.2.4: