fix deprecation warnings - constraint LinearAlgebra

[t-bltg]

This PR:

• fixes deprecation warning when using gaussjacobi with julia --depwarn=yes (introduced in Deprecate gausschebyshev and add gausschebyshevt, ..., gausschebyshevw #123);
• fixes test suite to avoid deprecation warnings when running under julia --depwarn=yes;
• add LinearAlgebra compat entry per PSA.

cc @hyrodium, @dlfivefifty.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (bd82113) 96.89% compared to head (3d04728) 96.89%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #132   +/-   ##
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  Coverage   96.89%   96.89%           
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  Files           9        9           
  Lines        1384     1384           
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  Hits         1341     1341           
  Misses         43       43           

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[hyrodium]

LGTM! Could you bump the version to v1.0.2?

[t-bltg]

Could you bump the version to v1.0.2?

Sure 😃, done !

[hyrodium]

Thank you for the excellent contribution!