Fix PRNG seed for random vectors and matrices in tests

[termoshtt]

For #336

Use rand_pcg::Mcg128Xsl64 as PRNG algorithm, and use specified seed

Note that PCG specifies a default value for the parameter:
state = 0xcafef00dd15ea5e5

[codecov]

Codecov Report

Merging #338 (4ea4f36) into master (f3a9f4c) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #338      +/-   ##
==========================================
+ Coverage   89.98%   90.01%   +0.02%     
==========================================
  Files          72       72              
  Lines        3925     4026     +101     
==========================================
+ Hits         3532     3624      +92     
- Misses        393      402       +9     

Impacted Files	Coverage Δ
ndarray-linalg/src/solve.rs	95.68% <ø> (ø)
ndarray-linalg/src/solveh.rs	75.49% <ø> (ø)
ndarray-linalg/tests/deth.rs	100.00% <ø> (ø)
ndarray-linalg/src/lobpcg/lobpcg.rs	90.67% <100.00%> (-0.55%)	⬇️
ndarray-linalg/src/lobpcg/svd.rs	87.65% <100.00%> (-1.10%)	⬇️
ndarray-linalg/tests/arnoldi.rs	100.00% <100.00%> (ø)
ndarray-linalg/tests/cholesky.rs	97.08% <100.00%> (+0.14%)	⬆️
ndarray-linalg/tests/convert.rs	100.00% <100.00%> (ø)
ndarray-linalg/tests/det.rs	98.59% <100.00%> (+0.02%)	⬆️
ndarray-linalg/tests/eigh.rs	100.00% <100.00%> (ø)
... and 18 more

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[termoshtt]

RNG for LOBPCG implementation is kept as it is, this PR only fix tests.