The kicad-library-utils have a nice visual diff tools which can be used to compare different versions of symbols.
Run it manually on a symbol library such as Regulator_Switching.kicad_sym using
python ~/dev/kicad-library-utils/html-diff/src/html_diff.py $(git rev-parse origin/master) Regulator_Switching.kicad_sym
This will compare the currently checked-out revision to the current origin/master revision (you might need to git fetch --all to update the current revision).
It will produce a directory Regulator_Switching.diff, containing one HTML files for each changed symbol.
Example:
Regulator_Switching.diff └── TPS62130.html