Introduce build tags

[dominikschulz]

Fixes #999

[codecov-io]

Codecov Report

Merging #1000 into master will decrease coverage by 0.16%.
The diff coverage is 38.36%.

@@            Coverage Diff             @@
##           master    #1000      +/-   ##
==========================================
- Coverage   63.43%   63.26%   -0.16%     
==========================================
  Files         173      180       +7     
  Lines        9966     9976      +10     
==========================================
- Hits         6321     6311      -10     
- Misses       2858     2879      +21     
+ Partials      787      786       -1

Impacted Files	Coverage Δ
pkg/action/xc/xc.go	39.72% <ø> (ø)	⬆️
main.go	27.69% <ø> (ø)	⬆️
pkg/backend/strings.go	40.82% <0%> (-43.05%)	⬇️
pkg/ctxutil/ctxutil.go	86.21% <0%> (-8.13%)	⬇️
pkg/action/clone.go	50% <0%> (-1.22%)	⬇️
pkg/store/sub/rcs.go	100% <100%> (+26.09%)	⬆️
pkg/store/sub/storage.go	100% <100%> (+83.82%)	⬆️
pkg/otp/otp.go	42.42% <100%> (ø)	⬆️
pkg/store/sub/crypto.go	100% <100%> (+12%)	⬆️
pkg/action/version.go	43.14% <100%> (+3.55%)	⬆️
... and 17 more

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