Freeze ko version to v0.9.3
Freeze ko version to v0.9.3

Freeze ko version to v0.9.3 as latest version fails to build on
go 1.16.13

Use `GO111MODULE=on` as `@version` syntax in go get will not work in
non GO mod

`go: can only use path@version syntax with 'go get' and 'go install' in
module-aware mode`

Signed-off-by: Nikhil Thomas <06117e966d039194d106149e879b10e553143831@redhat.com>

tektoncd/operator,tektoncd/operator,tektoncd/operator