CompatHelper: bump compat for RData to 1, (keep existing compat)

[github-actions]

This pull request changes the compat entry for the RData package from 0.5, 0.6, 0.7, 0.8 to 0.5, 0.6, 0.7, 0.8, 1.
This keeps the compat entries for earlier versions.

Note: I have not tested your package with this new compat entry.
It is your responsibility to make sure that your package tests pass before you merge this pull request.

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: +0.66 🎉

Comparison is base (b1a5959) 83.33% compared to head (5f95af2) 84.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #142      +/-   ##
==========================================
+ Coverage   83.33%   84.00%   +0.66%     
==========================================
  Files           3        4       +1     
  Lines          24       25       +1     
==========================================
+ Hits           20       21       +1     
  Misses          4        4              

see 1 file with indirect coverage changes

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[asinghvi17]

Do we care about Julia 1.0 going forward? If so we can loosen the Formatting.jl restrictions (we should also move to Format.jl btw, which is better maintained). If not, then we can simply remove that CI and upgrade compat with Julia to v1.3 or something, or potentially even v1.6.

Of course, users on Julia 1.0 can still install older versions.