Do not commit the locally built mapping sets.

Avoid committing the `uberon-local.sssom.tsv` mapping set to the
repository. This is not needed for now as the set depends only on
Uberon's -edit file, so it can always be re-generated whenever it is
needed even from a freshly cloned repository.

Also avoid committing the "meta" set `uberon.sssom.tsv`. It is merely a
compilation of the other mapping sets (including remote sets that *are*
committed to the repository) and so can also always be re-generated as
needed. In addition, the set is published as a release artifact, which
is how it should be accessed.

.gitignore

@@ -113,6 +113,8 @@ src/ontology/ed_definitions_merged.owl
 src/ontology/imports/*.obo
 imports/*.obo
 uberon-lastbuild.owl
+src/mappings/uberon-local.sssom.tsv
+src/mappings/uberon.sssom.tsv
 src/ontology/imports/*_terms_combined.txt
 src/ontology/merged-uberon-edit.owl
 src/ontology/mirror