add fitler and option of latest in forecast value read

[peterdudfield]

Pull Request

Description

add filter value and load distict on option on reading forecast values

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• [ ] Yes

Checklist:

• [ ] My code follows OCF's coding style guidelines
• [ ] I have performed a self-review of my own code
• [ ] I have made corresponding changes to the documentation
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have checked my code and corrected any misspellings

[codecov-commenter]

Codecov Report

Merging #30 (a2ca9fe) into main (4367d41) will increase coverage by 0.01%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main      #30      +/-   ##
==========================================
+ Coverage   97.86%   97.88%   +0.01%     
==========================================
  Files          16       16              
  Lines         563      568       +5     
==========================================
+ Hits          551      556       +5     
  Misses         12       12              

Impacted Files	Coverage Δ
nowcasting_datamodel/read/read.py	99.06% <100.00%> (+0.04%)	:arrow_up:

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