Rename Example_ANSIcolor to fix go test

[dbohdan]

go test passes in Go 1.17 but fails in Go 1.25 with this output:

# github.com/Ladicle/tabwriter_test
# [github.com/Ladicle/tabwriter_test]
./example_test.go:76:1: Example_ANSIcolor has malformed example suffix: ANSIcolor
FAIL    github.com/Ladicle/tabwriter [build failed]
FAIL

Renaming Example_ANSIcolor fixes the error. The test doesn't run in either Go version before or after the fix. It seems like it never ran.