go.mod: bump github.com/creack/pty from 1.1.9 to 1.1.15

Bumps [github.com/creack/pty](https://github.com/creack/pty) from 1.1.9 to 1.1.15.
- [Release notes](https://github.com/creack/pty/releases)
- [Commits](https://github.com/creack/pty/compare/v1.1.9...v1.1.15)

---
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>

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/anmitsu/go-shlex v0.0.0-20200514113438-38f4b401e2be // indirect
 	github.com/aws/aws-sdk-go v1.38.52
 	github.com/coreos/go-iptables v0.6.0
-	github.com/creack/pty v1.1.9
+	github.com/creack/pty v1.1.15
 	github.com/dave/jennifer v1.4.1
 	github.com/frankban/quicktest v1.13.0
 	github.com/gliderlabs/ssh v0.3.2

go.sum

@@ -80,8 +80,9 @@ github.com/coreos/go-semver v0.3.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3Ee
 github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e/go.mod h1:F5haX7vjVVG0kc13fIWeqUViNPyEJxv/OmvnBo0Yme4=
 github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
-github.com/creack/pty v1.1.9 h1:uDmaGzcdjhF4i/plgjmEsriH11Y0o7RKapEf/LDaM3w=
 github.com/creack/pty v1.1.9/go.mod h1:oKZEueFk5CKHvIhNR5MUki03XCEU+Q6VDXinZuGJ33E=
+github.com/creack/pty v1.1.15 h1:cKRCLMj3Ddm54bKSpemfQ8AtYFBhAI2MPmdys22fBdc=
+github.com/creack/pty v1.1.15/go.mod h1:MOBLtS5ELjhRRrroQr9kyvTxUAFNvYEK993ew/Vr4O4=
 github.com/daixiang0/gci v0.2.4/go.mod h1:+AV8KmHTGxxwp/pY84TLQfFKp2vuKXXJVzF3kD/hfR4=
 github.com/daixiang0/gci v0.2.7 h1:bosLNficubzJZICsVzxuyNc6oAbdz0zcqLG2G/RxtY4=
 github.com/daixiang0/gci v0.2.7/go.mod h1:+4dZ7TISfSmqfAGv59ePaHfNzgGtIkHAhhdKggP1JAc=