allow julia 1.6 installs

[AshtonSBradley]

Install on 1.6 fails with version conflicts, preventable by adding Manifest.toml to .gitignore.

Here I just did that and updated the package environment. Tests pass.

[codecov-io]

Codecov Report

Merging #6 (9beab95) into master (bf3b009) will increase coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master       #6      +/-   ##
==========================================
+ Coverage   98.37%   98.52%   +0.15%     
==========================================
  Files           9        8       -1     
  Lines         246      271      +25     
==========================================
+ Hits          242      267      +25     
  Misses          4        4              

Impacted Files	Coverage Δ
src/beta.jl	100.00% <0.00%> (ø)
src/stieltjes.jl	100.00% <0.00%> (ø)
src/utilities.jl	100.00% <0.00%> (ø)
src/bernoulli_n.jl	100.00% <0.00%> (ø)
src/Polylogarithms.jl
src/polylog.jl	99.33% <0.00%> (+0.06%)	⬆️
src/bernoulli_poly.jl	95.65% <0.00%> (+0.19%)	⬆️
src/gamma_derivatives.jl	96.87% <0.00%> (+0.32%)	⬆️
src/harmonic.jl	96.42% <0.00%> (+0.59%)	⬆️

---

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[AshtonSBradley]

Looks like some julia version logic needs updating with Travis... not sure what to suggest there

[codecov-commenter]

Codecov Report

Merging #6 (d0c5827) into master (bf3b009) will increase coverage by 0.15%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master       #6      +/-   ##
==========================================
+ Coverage   98.37%   98.52%   +0.15%     
==========================================
  Files           9        9              
  Lines         246      272      +26     
==========================================
+ Hits          242      268      +26     
  Misses          4        4              

Impacted Files	Coverage Δ
src/beta.jl	100.00% <0.00%> (ø)
src/stieltjes.jl	100.00% <0.00%> (ø)
src/utilities.jl	100.00% <0.00%> (ø)
src/bernoulli_n.jl	100.00% <0.00%> (ø)
src/polylog.jl	99.33% <0.00%> (+0.06%)	⬆️
src/bernoulli_poly.jl	95.65% <0.00%> (+0.19%)	⬆️
src/gamma_derivatives.jl	96.87% <0.00%> (+0.32%)	⬆️
src/harmonic.jl	96.42% <0.00%> (+0.59%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bf3b009...d0c5827. Read the comment docs.