Fix release script: add go mod tidy after go.mod changes

[ptabor]

Seems that additinal refresh of go.sum files is needed during the
release process after editing the versions of modules.

Discovered the problem while I was testing whether etcdutl is
properly included in the target binaries using:

DRY_RUN=true REPOSITORY=\`pwd\` BRANCH='branch-with-etcdutl' ./scripts/release 3.5.0-foobar.2

[codecov-commenter]

Codecov Report

Merging #12981 (2712c78) into main (9501e8e) will increase coverage by 6.38%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #12981      +/-   ##
==========================================
+ Coverage   46.10%   52.49%   +6.38%     
==========================================
  Files         409      315      -94     
  Lines       33636    26602    -7034     
==========================================
- Hits        15509    13965    -1544     
+ Misses      16119    10905    -5214     
+ Partials     2008     1732     -276     

Flag	Coverage Δ
all	52.49% <ø> (+6.38%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
client/pkg/v3/fileutil/dir_unix.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/fileutil/sync_linux.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/fileutil/read_dir.go	0.00% <0.00%> (-90.00%)	⬇️
client/pkg/v3/transport/timeout_transport.go	0.00% <0.00%> (-86.37%)	⬇️
client/pkg/v3/types/id.go	0.00% <0.00%> (-75.00%)	⬇️
pkg/grpc_testing/stub_server.go	0.00% <0.00%> (-64.00%)	⬇️
pkg/ioutil/util.go	0.00% <0.00%> (-63.64%)	⬇️
pkg/runtime/fds_linux.go	0.00% <0.00%> (-53.85%)	⬇️
client/pkg/v3/types/urlsmap.go	0.00% <0.00%> (-50.91%)	⬇️
client/pkg/v3/fileutil/lock_linux.go	19.44% <0.00%> (-36.12%)	⬇️
... and 128 more

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[lilic]

lgtm

[serathius]

LGTM,
In other projects I work we have static analysis that ensures that running go mod verify and go mod tidy passes without code diff on merged PRs. Would be happy to implement this.

[ptabor]

We perform the go mod tidy verification:

etcd/test.sh

Line 666 in f82b5cb

log_error "${PWD}/go.mod is not in sync with 'go mod tidy'"

as part of PASSES="fmt" ./test.sh. Didn't know about go mod verify. We might consider adding if its not verified by go build.