Update go for 3.5: 1.15.x -> 1.16.3

[ptabor]

Fixes #12732

[codecov-commenter]

Codecov Report

Merging #12874 (467a94c) into master (80586c5) will decrease coverage by 20.49%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master   #12874       +/-   ##
===========================================
- Coverage   71.99%   51.49%   -20.50%     
===========================================
  Files         427      424        -3     
  Lines       33813    33758       -55     
===========================================
- Hits        24342    17385     -6957     
- Misses       7519    14437     +6918     
+ Partials     1952     1936       -16     

Flag	Coverage Δ
all	51.49% <ø> (-20.50%)	⬇️

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

Impacted Files	Coverage Δ
client/v3/ordering/util.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/logutil/zap.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/types/slice.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/tlsutil/cipher_suites.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/transport/sockopt_unix.go	0.00% <0.00%> (-100.00%)	⬇️
client/v3/naming/endpoints/endpoints.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/transport/timeout_dialer.go	0.00% <0.00%> (-100.00%)	⬇️
client/pkg/v3/transport/timeout_listener.go	0.00% <0.00%> (-100.00%)	⬇️
...er/proxy/grpcproxy/adapter/watch_client_adapter.go	7.14% <0.00%> (-92.86%)	⬇️
client/pkg/v3/transport/keepalive_listener.go	0.00% <0.00%> (-92.31%)	⬇️
... and 216 more

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[spzala]

LGTM but one comment - we should update the reference here as well https://github.com/etcd-io/etcd#getting-etcd Thanks @ptabor

[ptabor]

Thank you @spzala. Fixed.

[spzala]

Thank you @spzala. Fixed.

Thank you @ptabor !!