Relax input type constraint to enable eltype promotion.

[N5N3]

Close #229.

[hyrodium]

Thanks for the contribution!
Btw, I'm not sure why I couldn't find the "approve and run" button here 🤔

I tried the tests on my local machine, and it thew the following error.

Test Summary: | Pass  Total
Util          |  201    201
Core: Test Failed at /home/hyrodium/.julia/dev/Rotations/test/2d.jl:21
  Expression: Angle2d((1, 0, 0, 1, 0))
    Expected: DimensionMismatch
      Thrown: ArgumentError
Stacktrace:
 [1] macro expansion
   @ ~/.julia/dev/Rotations/test/2d.jl:21 [inlined]
 [2] macro expansion
   @ ~/julia/julia-1.7.1/share/julia/stdlib/v1.7/Test/src/Test.jl:1283 [inlined]
 [3] macro expansion
   @ ~/.julia/dev/Rotations/test/2d.jl:11 [inlined]
 [4] macro expansion
   @ ~/julia/julia-1.7.1/share/julia/stdlib/v1.7/Test/src/Test.jl:1283 [inlined]
 [5] top-level scope
   @ ~/.julia/dev/Rotations/test/2d.jl:10
Test Summary:                    | Pass  Fail  Total
2d Rotations                     | 4864     1   4865
  Core                           |   10     1     11
  Unitful                        |    4            4
  Identity rotation checks       |   12           12
  zero checks                    |   18           18
  Testing inv()                  | 1000         1000
  Testing norm() and normalize() |  600          600
  Rotate Points                  |  202          202
  Rotate Unitful Points          |  606          606
  Compose rotations              |  800          800
  Convert rotations              |  200          200
  Types and products             |   12           12
  RotMatrix{2} vs Angle2d        |  400          400
  Angle2d                        |  700          700
  angle                          |  300          300
ERROR: LoadError: Some tests did not pass: 4864 passed, 1 failed, 0 errored, 0 broken.
in expression starting at /home/hyrodium/.julia/dev/Rotations/test/2d.jl:4
in expression starting at /home/hyrodium/.julia/dev/Rotations/test/runtests.jl:17
ERROR: Package Rotations errored during testing

This seems to be caused by StaticArrays throwing ArgumentError for SMatrix{2,2}(1,0,0,1,0). But I think this should be DimensionMismatch.

[N5N3]

Oops, I forgot to swith back to StaticArrays's master branch when testing this. (With JuliaArrays/StaticArrays.jl#1016, SMatrix{2,2}(1,0,0,1,0) throws a DimensionMismatch).
We could replace it with SArray{Tuple{2,2}} as, SArray{Tuple{2,2}}(1,2,3,4,5) throws a DimensionMismatch.

[codecov]

Codecov Report

Merging #230 (fc774f1) into master (a12cb6c) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #230   +/-   ##
=======================================
  Coverage   88.45%   88.45%           
=======================================
  Files          16       16           
  Lines        1602     1602           
=======================================
  Hits         1417     1417           
  Misses        185      185           

Impacted Files	Coverage Δ
src/core_types.jl	95.62% <100.00%> (ø)

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[hyrodium]

LGTM!
After the last commit & push, the "approve and run" button has appeared.