cli/command/container: fix missing go:build tag

[thaJeztah]

• relates to https://github.com/docker/compose/pull/12297#issuecomment-2478450487
• relates to https://github.com/docker/cli/pull/4723

---

make shell
make -C ./internal/gocompat/

GO111MODULE=on go test -v
# github.com/docker/cli/cli/command/container
../../cli/command/container/completion.go:37:28: implicit function instantiation requires go1.18 or later (-lang was set to go1.16; check go.mod)
../../cli/command/container/completion.go:82:25: implicit function instantiation requires go1.18 or later (-lang was set to go1.16; check go.mod)
../../cli/command/container/completion.go:92:27: implicit function instantiation requires go1.18 or later (-lang was set to go1.16; check go.mod)
FAIL    gocompat [build failed]

- A picture of a cute animal (not mandatory but encouraged)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 59.50%. Comparing base (4adbb18) to head (d1d5353). Report is 2 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #5621 +/- ## ======================================= Coverage 59.50% 59.50% ======================================= Files 346 346 Lines 29365 29365 ======================================= Hits 17474 17474 Misses 10916 10916 Partials 975 975 ```