Remove (::<AbstractString)(::GapObj)

[fingolfin]

This is part of PR #936 by @lgoettgens and already mergable by itself.

It is also technically a breaking change, I guess, although I don't know of any code relying on this... but who knows....

[lgoettgens]

I do not see any difference between this and #936 (except for toggling the Aqua test switch).
Or is this intended to have a separate release note item for the breaking change?

[codecov]

Codecov Report

Merging #941 (81f63c6) into master (1ad0308) will decrease coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #941      +/-   ##
==========================================
- Coverage   75.72%   75.71%   -0.02%     
==========================================
  Files          51       51              
  Lines        4161     4159       -2     
==========================================
- Hits         3151     3149       -2     
  Misses       1010     1010              

Files Changed	Coverage
src/constructors.jl	ø
src/gap_to_julia.jl	100.00%

[fingolfin]

The other PR was marked as draft and I thought there is more work to be done there, so I thought we could merge this part of it already now -- but I now see you actually "completed" PR #936 now, in which case I am of course also happy to just merge that one directly :-)