Bump github.com/creack/pty from 1.1.18 to 1.1.21 (#2825)

Bumps [github.com/creack/pty](https://github.com/creack/pty) from 1.1.18 to 1.1.21.
- [Release notes](https://github.com/creack/pty/releases)
- [Commits](creack/pty@v1.1.18...v1.1.21)

---
updated-dependencies:
- dependency-name: github.com/creack/pty
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

go.mod

@@ -19,7 +19,7 @@ require (
 	github.com/SermoDigital/jose v0.9.2-0.20161205224733-f6df55f235c2
 	github.com/blang/semver/v4 v4.0.0
 	github.com/cloudfoundry/bosh-cli v6.4.1+incompatible
-	github.com/creack/pty v1.1.18
+	github.com/creack/pty v1.1.21
 	github.com/cyphar/filepath-securejoin v0.2.4
 	github.com/docker/distribution v2.8.3+incompatible
 	github.com/fatih/color v1.16.0

go.sum

@@ -56,8 +56,8 @@ github.com/codegangsta/negroni v1.0.0/go.mod h1:v0y3T5G7Y1UlFfyxFn/QLRU4a2EuNau2
 github.com/cppforlife/go-patch v0.1.0 h1:I0fT+gFTSW4xWwvaTaUUVjr9xxjNXJ4naGc01BeQjwY=
 github.com/cppforlife/go-patch v0.1.0/go.mod h1:67a7aIi94FHDZdoeGSJRRFDp66l9MhaAG1yGxpUoFD8=
 github.com/creack/pty v1.1.7/go.mod h1:lj5s0c3V2DBrqTV7llrYr5NG6My20zk30Fl46Y7DoTY=
-github.com/creack/pty v1.1.18 h1:n56/Zwd5o6whRC5PMGretI4IdRLlmBXYNjScPaBgsbY=
-github.com/creack/pty v1.1.18/go.mod h1:MOBLtS5ELjhRRrroQr9kyvTxUAFNvYEK993ew/Vr4O4=
+github.com/creack/pty v1.1.21 h1:1/QdRyBaHHJP61QkWMXlOIBfsgdDeeKfK8SYVUWJKf0=
+github.com/creack/pty v1.1.21/go.mod h1:MOBLtS5ELjhRRrroQr9kyvTxUAFNvYEK993ew/Vr4O4=
 github.com/cyphar/filepath-securejoin v0.2.4 h1:Ugdm7cg7i6ZK6x3xDF1oEu1nfkyfH53EtKeQYTC3kyg=
 github.com/cyphar/filepath-securejoin v0.2.4/go.mod h1:aPGpWjXOXUn2NCNjFvBE6aRxGGx79pTxQpKOJNYHHl4=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=