remove gotest.tools for testing

[thaJeztah]

Reduce the number of dependencies for this module.

[thaJeztah]

Looks like I had this branch created somewhere in 2020, but never pushed, but I just discovered why; I was waiting for old go versions to be dropped;

Error: ./term_test.go:21:3: t.Cleanup undefined (type *testing.T has no field or method Cleanup)
FAIL	github.com/moby/term [build failed]
?   	github.com/moby/term/windows	[no test files]
FAIL
Error: Process completed with exit code 2.

Let me do so first

[thaJeztah]

Opened #33

Let me include this in #21