Try converting Array values to same type in constructor

[soininen]

This PR makes Array.__init__() try to convert all values to the same type if the types are not consistent before raising an exception.

Re spine-tools/Spine-Toolbox#2017

Checklist before merging

• [x] Documentation (also in Toolbox repo) is up-to-date
• [x] Release notes in Toolbox repo have been updated
• [x] Unit tests have been added/updated accordingly
• [x] Code has been formatted by black
• [x] Unit tests pass

[codecov-commenter]

Codecov Report

Patch coverage has no change and project coverage change: -0.02 :warning:

Comparison is base (993821d) 75.30% compared to head (2217099) 75.29%.

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Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #233 +/- ## ========================================== - Coverage 75.30% 75.29% -0.02% ========================================== Files 76 76 Lines 10890 10893 +3 Branches 2365 2366 +1 ========================================== + Hits 8201 8202 +1 - Misses 2253 2255 +2 Partials 436 436 ``` | [Impacted Files](https://codecov.io/gh/spine-tools/Spine-Database-API/pull/233?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools) | Coverage Δ | | |---|---|---| | [spinedb\_api/parameter\_value.py](https://codecov.io/gh/spine-tools/Spine-Database-API/pull/233?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools#diff-c3BpbmVkYl9hcGkvcGFyYW1ldGVyX3ZhbHVlLnB5) | `79.20% <0.00%> (-0.17%)` | :arrow_down: | | [spinedb\_api/spine\_io/importers/excel\_reader.py](https://codecov.io/gh/spine-tools/Spine-Database-API/pull/233?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools#diff-c3BpbmVkYl9hcGkvc3BpbmVfaW8vaW1wb3J0ZXJzL2V4Y2VsX3JlYWRlci5weQ==) | `66.46% <ø> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=spine-tools)

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