Fix unit tests

[GegznaV]

I installed unmixR locally. I ran the unit tests in two ways and they failed on my machine.

1. unmixR.unittest()

2. devtools::test()

Results (truncated):

ℹ Testing unmixR
✔ | F W S  OK | Context
...
────────────────────────────────────────────────────
...
✖ | 2   2   7 | vca [0.2s] 
────────────────────────────────────────────────────

Error (vca.default.R:76:7): correct results for all available methods: triangle data
Error in `vca.default(.testdata$x, p = 3, method = i)`: object '.Random.seed' not found
Backtrace:
 1. testthat::expect_equal(...)
      at unmixR/R/vca.default.R:76:6
 5. unmixR::vca.default(.testdata$x, p = 3, method = i)
      at unmixR/R/vca.R:63:2
...
Error (vca.default.R:104:5): vca output is sorted
Error in `vca.default(.testdata$x, p = 3)`: object '.Random.seed' not found
Backtrace:
 1. unmixR::vca(.testdata$x, p = 3)
      at unmixR/R/vca.default.R:104:4
 2. unmixR::vca.default(.testdata$x, p = 3)
      at unmixR/R/vca.R:63:2
────────────────────────────────────────────────────
✖ | 1       5 | simplex_volume                      
────────────────────────────────────────────────────
Failure (simplex.R:106:5): correct volumes for triangle data
simplex_volume(triangle_2d, factorial = FALSE) not equal to `area_2d`.
1/1 mismatches
[1] 1 - 0.5 == 0.5

...

══ Results ═════════════════════════════════════════
Duration: 0.8 s

── Skipped tests  ──────────────────────────────────
• known issue: #36 (1)
• LDU skipped: known issue #38 (2)
• temporarily disabled (1)

[ FAIL 3 | WARN 0 | SKIP 4 | PASS 49 ]

Can these be fixed, @rguliev, @bryanhanson?

---

Tasks:

• Fix unittest results reporter #45
• Fix unit tests:
  • Fix unit tests which were skipped and marked as FIXME in Add GHA workflows (R CMD check, test coverage, build pkgdown website) #38
  • Fix .Random.seed related error on R-devel #47

[GegznaV]

Is an update related to a newer version of either R, or testthat, or other packages are needed?