generalize to handle AbstractStrings in time_series_metatdata parsing

[codecov[bot]]

Codecov Report

Merging #270 (62c3139) into master (5438fee) will decrease coverage by 0.24%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #270      +/-   ##
==========================================
- Coverage   78.51%   78.27%   -0.25%     
==========================================
  Files          43       43              
  Lines        3575     3438     -137     
==========================================
- Hits         2807     2691     -116     
+ Misses        768      747      -21     

Flag	Coverage Δ
unittests	78.27% <ø> (-0.25%)	:arrow_down:

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

Impacted Files	Coverage Δ
src/time_series_parser.jl	70.00% <ø> (-0.24%)	:arrow_down:
src/utils/utils.jl	64.58% <0.00%> (-1.57%)	:arrow_down:
src/utils/print.jl	52.10% <0.00%> (-1.10%)	:arrow_down:
src/utils/generate_structs.jl	84.68% <0.00%> (-0.91%)	:arrow_down:
src/internal.jl	78.84% <0.00%> (-0.79%)	:arrow_down:
src/probabilistic.jl	77.19% <0.00%> (-0.78%)	:arrow_down:
src/scenarios.jl	83.67% <0.00%> (-0.65%)	:arrow_down:
src/deterministic.jl	81.53% <0.00%> (-0.56%)	:arrow_down:
src/utils/recorder_events.jl	91.39% <0.00%> (-0.53%)	:arrow_down:
src/components.jl	92.56% <0.00%> (-0.52%)	:arrow_down:
... and 17 more