Add myself as test directory codeowner

I noticed when someone created a test-only modifying PR that no
one got pinged for review. Don't want that to happen. And test
corresponds logically to the framework so it makes sense to pair
the ownership

refs #0

CODEOWNERS

@@ -78,3 +78,5 @@
 /scripts/update_and_rebuild_petsc_alt.sh @cticenhour @milljm @loganharbour
 /scripts/configure_libmesh.sh @cticenhour @milljm @loganharbour @roystgnr
 /scripts/update_and_rebuild_libmesh.sh @cticenhour @milljm @loganharbour @roystgnr
+
+/test @lindsayad