[cmake] reset version to 0.1.0

[wgtdkp]

According to https://semver.org/, version 1.0.0 defines the stable public API. But we are currently changing the public API frequently and this situation may continue before we finishing building Commissioner Service with ot-commissioner.

This PR resets the version to 0.1.0 to indicates that the public API is not stable.

Major version zero (0.y.z) is for initial development. Anything MAY change at any time. The public API SHOULD NOT be considered stable. Version 1.0.0 defines the public API. The way in which the version number is incremented after this release is dependent on this public API and how it changes.

[codecov-commenter]

Codecov Report

Merging #111 into master will decrease coverage by 12.66%. The diff coverage is n/a.

@@             Coverage Diff             @@
##           master     #111       +/-   ##
===========================================
- Coverage   50.09%   37.42%   -12.67%     
===========================================
  Files          56       56               
  Lines        5392     5392               
===========================================
- Hits         2701     2018      -683     
- Misses       2691     3374      +683     

Impacted Files	Coverage Δ
src/common/utils.hpp	47.82% <0.00%> (-52.18%)	:arrow_down:
src/library/commissioner_impl.cpp	8.75% <0.00%> (-36.50%)	:arrow_down:
src/library/tlv.cpp	24.89% <0.00%> (-24.48%)	:arrow_down:
src/library/commissioner_safe.cpp	28.51% <0.00%> (-22.90%)	:arrow_down:
src/library/network_data.cpp	58.97% <0.00%> (-17.95%)	:arrow_down:
src/app/file_logger.cpp	66.66% <0.00%> (-11.77%)	:arrow_down:
src/library/error.cpp	0.00% <0.00%> (-10.00%)	:arrow_down:
src/app/cli/interpreter.cpp	13.65% <0.00%> (-9.05%)	:arrow_down:
src/app/commissioner_app.cpp	8.34% <0.00%> (-8.05%)	:arrow_down:
src/app/json.cpp	44.78% <0.00%> (-5.22%)	:arrow_down:
... and 6 more