Added ETCD as backend

[alejandrojnm]

I have decided to add ETCD as a new backend since it is well integrated into Kubernetes. All the tests and the benchmarks pass without any problem, but I left that section in the README empty because I run it all in a Macbook pro M1, so I think it would be preferable to run it on the same machine again.

[majst01]

Nice, thanks for the effort, was thinking also to add this but hadn't enough time. Can you look for the linter errors ?

[majst01]

still a linter issue, try running golangci-lint run -p bugs -p unused locally

[alejandrojnm]

@majst01 hi, the problem is TLS InsecureSkipVerify set true. but it is possible to set to true that variable, in our case we use a custom SSL cert so we need to pass InsecureSkipVerify= true.

[majst01]

@majst01 hi, the problem is TLS InsecureSkipVerify set true. but it is possible to set to true that variable, in our case we use a custom SSL cert so we need to pass InsecureSkipVerify= true.

you can silent this linter error with `// nolint:gosec`` bevore the line of the complain

[alejandrojnm]

Checking all the test now

[codecov-commenter]

Codecov Report

Merging #74 (e1fe134) into master (8b60c49) will decrease coverage by 2.22%.
The diff coverage is 64.10%.

@@            Coverage Diff             @@
##           master      #74      +/-   ##
==========================================
- Coverage   78.50%   76.28%   -2.23%     
==========================================
  Files           7        8       +1     
  Lines         642      759     +117     
==========================================
+ Hits          504      579      +75     
- Misses         74       99      +25     
- Partials       64       81      +17     

Impacted Files	Coverage Δ
etcd.go	64.10% <64.10%> (ø)

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[majst01]

Looks good, one small nit. Its slightly faster than postgres but 5x more allocs

[alejandrojnm]

Hi @majst01 I think all is good now

[majst01]

Awesome, thanks for this contribution.