[Security] Bump sshpk from 1.13.1 to 1.15.2

Bumps [sshpk](https://github.com/joyent/node-sshpk) from 1.13.1 to 1.15.2. **This update includes security fixes.**
- [Release notes](https://github.com/joyent/node-sshpk/releases)
- [Commits](TritonDataCenter/node-sshpk@v1.13.1...v1.15.2)

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

yarn.lock

@@ -4605,6 +4605,10 @@ safe-buffer@^5.0.1, safe-buffer@^5.1.0, safe-buffer@^5.1.1, safe-buffer@~5.1.0,
   version "5.1.1"
   resolved "https://registry.yarnpkg.com/safe-buffer/-/safe-buffer-5.1.1.tgz#893312af69b2123def71f57889001671eeb2c853"
 
+safer-buffer@^2.0.2:
+  version "2.1.2"
+  resolved "https://registry.yarnpkg.com/safer-buffer/-/safer-buffer-2.1.2.tgz#44fa161b0187b9549dd84bb91802f9bd8385cd6a"
+
 sax@~1.2.1:
   version "1.2.4"
   resolved "https://registry.yarnpkg.com/sax/-/sax-1.2.4.tgz#2816234e2378bddc4e5354fab5caa895df7100d9"
@@ -4769,17 +4773,17 @@ sprintf-js@~1.0.2:
   resolved "https://registry.yarnpkg.com/sprintf-js/-/sprintf-js-1.0.3.tgz#04e6926f662895354f3dd015203633b857297e2c"
 
 sshpk@^1.7.0:
-  version "1.13.1"
-  resolved "https://registry.yarnpkg.com/sshpk/-/sshpk-1.13.1.tgz#512df6da6287144316dc4c18fe1cf1d940739be3"
+  version "1.15.2"
+  resolved "https://registry.yarnpkg.com/sshpk/-/sshpk-1.15.2.tgz#c946d6bd9b1a39d0e8635763f5242d6ed6dcb629"
   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"
+    getpass "^0.1.1"
     jsbn "~0.1.0"
+    safer-buffer "^2.0.2"
     tweetnacl "~0.14.0"
 
 stackframe@^0.3.1: