Remove useless read method in SExtractor reader.

- No need to store the output in `self.table` and return it.
- `self.cols` already exist in the parent method.
Default reader's outputter is already instantiated in reader's init.
Avoid computing the number of cols at each iteration.
update included erfa to v1.1.1
Add erfa version comment
Ensure that quantity operations with incompatible types give a useful TypeError
Merge pull request #2934 from mhvk/quantity-non-number-operations

Ensure that quantity operations with incompatible types give a useful TypeError
Merge pull request #2947 from saimn/ascii-small-things

Small enhancements for io.ascii
add changelog entry

[ci skip]
Merge pull request #2971 from eteq/erfa-v1.1.1

Update to ERFA v1.1.1
Regression tests against #2083 (rounding issues near leap seconds)
Merge pull request #2978 from mhvk/time-leap-seconds-check

Regression tests against #2083 (rounding issues near leap seconds)
Change __repr__ of coordinates to seperate data and frame attributes
Add coordinate __repr__ change to CHANGES.rst
Update coordinate frame doc with different coordinate  repr
Note coordinate repr changes in two places in CHANGES.rst

[ci skip]
Merge pull request #2882 from sargas/issue2704

Seperate frame and data parameters in SkyCoord.__repr__
Support file output from FITS diff given path name
Fix the reporting of errors in files where TEST_UNICODE_LITERALS is
enabled.
Merge pull request #2987 from mdboom/test/fix-unicode-literals-error-reporting

Tests with TEST_UNICODE_LITERALS don't report errors correctly