Delete redundant isequal method

[fingolfin]

The default method already delegates to ==

Extracted from PR #1854

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.15%. Comparing base (983f6ec) to head (1690463).
Report is 7 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1875      +/-   ##
==========================================
- Coverage   88.15%   88.15%   -0.01%     
==========================================
  Files         120      120              
  Lines       30250    30248       -2     
==========================================
- Hits        26668    26666       -2     
  Misses       3582     3582              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[joschmitt]

Just to say: the default method in

AbstractAlgebra.jl/src/Rings.jl

Line 7 in b02dca9

function isequal(a::RingElem, b::RingElem)

first checks the parents. However, currently the behaviour of both versions is exactly the same because == does not throw an error for TotFracs with different parents.