plugins: add go mod tidy due to Go1.16 changes

[aschmahmann]

@DeedleFake seems to have run into this. Go 1.16 requires the go.sum files be in sync.

Here is a local run with the error. Note: the use of Go 1.18 here means this will fail at run time due to quic and me needing Go <= 1.16, but that's not the point here.

adin@AdinPC:~/go/src/github.com/ipfs/fs-repo-migrations$ ./build-plugin.sh 11-to-12 github.com/ipfs/go-ds-s3@v0.7.0
~/go/src/github.com/ipfs/fs-repo-migrations/fs-repo-11-to-12 ~/go/src/github.com/ipfs/fs-repo-migrations
~/go/src/github.com/ipfs/fs-repo-migrations
===> Getting go-ipfs branch v0.8.0
Cloning into '/tmp/tmp.GCfm71n5Ipmigration_build/go-ipfs'...
remote: Enumerating objects: 109034, done.
remote: Counting objects: 100% (83/83), done.
remote: Compressing objects: 100% (68/68), done.
remote: Total 109034 (delta 26), reused 34 (delta 13), pack-reused 108951
Receiving objects: 100% (109034/109034), 45.47 MiB | 33.59 MiB/s, done.
Resolving deltas: 100% (72582/72582), done.
Note: switching to 'ce693d7e81e0206b3afbce30333c21a36a9f094b'.

You are in 'detached HEAD' state. You can look around, make experimental
changes and commit them, and you can discard any commits you make in this
state without impacting any branches by switching back to a branch.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -c with the switch command. Example:

  git switch -c <new-branch-name>

Or undo this operation with:

  git switch -

Turn off this advice by setting config variable advice.detachedHead to false

===> Bundling plugin github.com/ipfs/go-ds-s3@v0.7.0 info go-ipfs for migration
plugin version: v0.7.0
/tmp/tmp.GCfm71n5Ipmigration_build/go-ipfs ~/go/src/github.com/ipfs/fs-repo-migrations
go: added github.com/ipfs/go-ds-s3 v0.7.0
~/go/src/github.com/ipfs/fs-repo-migrations
For github.com/ipfs/go-ds-s3, load 'plugin *' [y/n]?y
===> Building go-ipfs with datastore plugins
make: Entering directory '/tmp/tmp.GCfm71n5Ipmigration_build/go-ipfs'
go version go1.18.1 linux/amd64
bin/check_go_version 1.14.4
plugin/loader/preload.sh > plugin/loader/preload.go
go fmt plugin/loader/preload.go >/dev/null
go mod tidy
go build  "-asmflags=all='-trimpath='" "-gcflags=all='-trimpath='" -ldflags="-X "github.com/ipfs/go-ipfs".CurrentCommit=ce693d7e8-dirty" -o "cmd/ipfs/ipfs" "github.com/ipfs/go-ipfs/cmd/ipfs"
make: Leaving directory '/tmp/tmp.GCfm71n5Ipmigration_build/go-ipfs'

===> Building migration fs-repo-11-to-12 with plugins
~/go/src/github.com/ipfs/fs-repo-migrations/fs-repo-11-to-12 ~/go/src/github.com/ipfs/fs-repo-migrations
go: github.com/ipfs/go-ipfs@v0.8.0 requires
        github.com/ipfs/go-ds-s3@v0.7.0: missing go.sum entry; to add it:
        go mod download github.com/ipfs/go-ds-s3
go: github.com/ipfs/go-ipfs@v0.8.0 requires
        github.com/ipfs/go-ds-s3@v0.7.0: missing go.sum entry; to add it:
        go mod download github.com/ipfs/go-ds-s3

[aschmahmann]

This seems like an easy PR to merge, but asking for reviews since:

1. PR reviews are good in case people make mistakes 😄
2. We've seen a bunch of this related to the Go 1.16 changes and wanted to flag we may see more across the codebase for any areas not regularly checked by CI

[BigLep]

@guseggert : can you get this reviewed/merged?