Switch to "go install" from "go get -u" for some packages

[KEINOS]

Some packages require updating even using the latest image.

Tools environment: GOPATH=/go, GOBIN=/go/bin
Installing 9 tools at the configured GOBIN: /go/bin in module mode.
  gopkgs
  go-outline
  gotests
  gomodifytags
  impl
  goplay
  dlv
  staticcheck
  gopls

Installing github.com/uudashr/gopkgs/v2/cmd/gopkgs (/go/bin/gopkgs) SUCCEEDED
Installing github.com/ramya-rao-a/go-outline (/go/bin/go-outline) SUCCEEDED
Installing github.com/cweill/gotests/gotests (/go/bin/gotests) SUCCEEDED
Installing github.com/fatih/gomodifytags (/go/bin/gomodifytags) SUCCEEDED
Installing github.com/josharian/impl (/go/bin/impl) SUCCEEDED
Installing github.com/haya14busa/goplay/cmd/goplay (/go/bin/goplay) SUCCEEDED
Installing github.com/go-delve/delve/cmd/dlv (/go/bin/dlv) SUCCEEDED
Installing honnef.co/go/tools/cmd/staticcheck (/go/bin/staticcheck) SUCCEEDED
Installing golang.org/x/tools/gopls (/go/bin/gopls) SUCCEEDED

All tools successfully installed. You are ready to Go :).

Possible Cause

This might be using go get -u rather than go install since it's in module mode by default.

VSCode-Dev-Container-Go/Dockerfile

Lines 55 to 74 in c1a618e

	RUN \
	# Packages that Go team suggests to install
	go get -u "github.com/ramya-rao-a/go-outline@latest" && \
	go get -u "github.com/cweill/gotests/gotests@latest" && \
	go get -u "github.com/fatih/gomodifytags@latest" && \
	go get -u "github.com/uudashr/gopkgs/v2/cmd/gopkgs@latest" && \
	go get -u "github.com/josharian/impl@latest" && \
	go get -u "github.com/haya14busa/goplay/cmd/goplay@latest" && \
	go get -u "github.com/go-delve/delve/cmd/dlv@latest" && \
	go get -u "honnef.co/go/tools/cmd/staticcheck@latest" && \
	# Fix issue #22
	go get "golang.org/x/tools/gopls@latest" && \
	# Packages that KEINOS commonly uses
	go get -u "github.com/msoap/go-carpet@latest" && \
	go get -u "mvdan.cc/sh/v3/cmd/shfmt@latest" && \
	go get -u "github.com/tenntenn/goplayground/cmd/gp@latest" && \
	go get -u "github.com/princjef/gomarkdoc/cmd/gomarkdoc@latest" && \
	go get -u "github.com/nicksnyder/go-i18n/v2/goi18n@latest" && \
	go get -u "mvdan.cc/gofumpt@latest" && \
	go get -u "github.com/jessfraz/dockfmt@latest"