Bug: Pow specialisation was being added to expm dispatcher.

[AGaliciaMartinez]

I really think that adding an assert in the Tests for the specialisations that checks whether the tested specialisation have been added correctly would prevent this kind of mistakes. It would only have to check whether the _specialisations attribute has the new specialisation that is being tested.

[coveralls]

Pull Request Test Coverage Report for Build 1133098068

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.553%

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Totals
Change from base Build 1112911961:	0.0%
Covered Lines:	243
Relevant Lines:	257

---

💛 - Coveralls

[AGaliciaMartinez]

I will simply merge this PR as the fix is simple and I need this for another PR to work.

[coveralls]

Pull Request Test Coverage Report for Build 1133098068

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 94.553%

---

Totals
Change from base Build 1112911961:	0.0%
Covered Lines:	243
Relevant Lines:	257

---

💛 - Coveralls