Review julia compatibility in readme #313

[hpmouton]

This pull request addresses issue #313 by correcting the Julia version compatibility information in the README. The current README states "Julia 1.3 and up". The corrected version now accurately reflects the correct compatibility as "Julia 1.6 and up."

Changes Made:

• Updated README.md to specify Julia version compatibility as "Julia 1.6 and up" on line 30.

Related Issue: Closes #313

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 96.52%. Comparing base (4d87714) to head (005af1b). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #320 +/- ## ======================================= Coverage 96.52% 96.52% ======================================= Files 15 15 Lines 1065 1065 ======================================= Hits 1028 1028 Misses 37 37 ```

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[github-actions[bot]]

Package name	latest	stable
CaNNOLeS.jl
DCISolver.jl
FletcherPenaltySolver.jl
JSOSolvers.jl
Krylov.jl
NLPModels.jl
NLPModelsModifiers.jl
PROPACK.jl
Percival.jl
QuadraticModels.jl
SolverTools.jl

[dpo]

Thank you!