build(deps): bump github.com/pkg/errors from 0.8.1 to 0.9.1 in /sdk

Bumps [github.com/pkg/errors](https://github.com/pkg/errors) from 0.8.1 to 0.9.1.
- [Release notes](https://github.com/pkg/errors/releases)
- [Commits](https://github.com/pkg/errors/compare/v0.8.1...v0.9.1

)

---
updated-dependencies:
- dependency-name: github.com/pkg/errors
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

sdk/go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/kr/pretty v0.2.0 // indirect
 	github.com/mattn/go-isatty v0.0.12 // indirect
 	github.com/mitchellh/go-testing-interface v1.0.0
-	github.com/pkg/errors v0.8.1
+	github.com/pkg/errors v0.9.1
 	github.com/stretchr/testify v1.4.0
 	golang.org/x/sys v0.0.0-20200124204421-9fbb57f87de9
 	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect

sdk/go.sum

@@ -24,8 +24,8 @@ github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHX
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
 github.com/mitchellh/go-testing-interface v1.0.0 h1:fzU/JVNcaqHQEcVFAKeR41fkiLdIPrefOvVG1VZ96U0=
 github.com/mitchellh/go-testing-interface v1.0.0/go.mod h1:kRemZodwjscx+RGhAo8eIhFbs2+BFgRtFPeD/KE+zxI=
-github.com/pkg/errors v0.8.1 h1:iURUrRGxPUNPdy5/HRSm+Yj6okJ6UtLINN0Q9M4+h3I=
-github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=
+github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=