Increase leniency of semver parsing

[nhynes]

Not all sources of semvers provide three fields. For instance, runtime.Version() will return only major and minor when it's part of a release build (usage). This fixes oasis-node startup issues.

[nhynes]

or maybe nil?

[pro-wh]

I like that this preallocates

[nhynes]

no, I mean like Option<u16>

[codecov]

Codecov Report

Merging #2742 into master will decrease coverage by 0.08%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #2742      +/-   ##
==========================================
- Coverage      63%   62.92%   -0.09%     
==========================================
  Files         383      383              
  Lines       36094    36094              
==========================================
- Hits        22742    22713      -29     
+ Misses      10525    10516       -9     
- Partials     2827     2865      +38

Impacted Files	Coverage Δ
go/common/version/version.go	84% <66.66%> (ø)	⬆️
go/consensus/tendermint/api/api.go	73.58% <0%> (-15.1%)	⬇️
go/storage/metrics.go	72.64% <0%> (-7.7%)	⬇️
go/storage/api/root_cache.go	70.11% <0%> (-6.9%)	⬇️
go/runtime/tagindexer/tagindexer.go	68.47% <0%> (-4.35%)	⬇️
go/storage/client/client.go	75.63% <0%> (-3.79%)	⬇️
go/storage/mkvs/urkel/urkel.go	85.71% <0%> (-3.58%)	⬇️
go/storage/database/database.go	74.56% <0%> (-3.51%)	⬇️
go/storage/mkvs/urkel/insert.go	86.39% <0%> (-2.73%)	⬇️
go/runtime/transaction/transaction.go	75.9% <0%> (-2.41%)	⬇️
... and 13 more

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[nhynes]

mdlint is giving spurious errors
.changelog/2742.bugfix.md:4:6 MD034/no-bare-urls Bare URL used [Context: "https://golang.org/pkg/runtime..."

[foo][0]
[0]: https://bar

is not a bare url

[pro-wh]

Does Go claim to use semver?

[pro-wh]

if I search "semver," I find this https://semver.org/#spec-item-2:

A normal version number MUST take the form X.Y.Z

and then they don't explain what "normal" refers to

[pro-wh]

alright seeing as we're elsewhere cramming the Go runtime version down parseSemVerStr's throat, we might as well not make our node panic