rename ROOT var to CS_ROOT in Makefile

[blotus]

Closes #1753

[codecov-commenter]

Codecov Report

Merging #1755 (56c8049) into master (1f06f24) will decrease coverage by 0.32%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1755      +/-   ##
==========================================
- Coverage   49.39%   49.06%   -0.33%     
==========================================
  Files         117      117              
  Lines       17590    17590              
==========================================
- Hits         8688     8630      -58     
- Misses       7878     7948      +70     
+ Partials     1024     1012      -12     

Flag	Coverage Δ
func-crowdsec	45.84% <ø> (-7.03%)	⬇️
func-cscli	41.61% <ø> (-0.06%)	⬇️
unit-windows	53.40% <ø> (+0.14%)	⬆️

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

Impacted Files	Coverage Δ
cmd/crowdsec/api.go	51.85% <0.00%> (-27.78%)	⬇️
cmd/crowdsec/serve.go	23.23% <0.00%> (-17.85%)	⬇️
cmd/crowdsec/metrics.go	27.63% <0.00%> (-17.11%)	⬇️
cmd/crowdsec-cli/machines.go	55.12% <0.00%> (-1.07%)	⬇️
pkg/apiserver/apic.go	78.25% <0.00%> (+0.63%)	⬆️
pkg/acquisition/modules/file/file.go	66.28% <0.00%> (+0.86%)	⬆️
pkg/cwhub/loader.go	64.41% <0.00%> (+0.92%)	⬆️
pkg/cwhub/download.go	52.17% <0.00%> (+1.44%)	⬆️
pkg/cwhub/install.go	47.69% <0.00%> (+3.07%)	⬆️

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