fix codespell CI (#215)

we were targeting the wrong branch for PRs

Author: zingale

.github/workflows/codespell.yml

@@ -3,11 +3,10 @@ name: codespell
 on:
   push:
     branches:
-      - development
       - main
   pull_request:
     branches:
-      - development
+      - main
 
 jobs:
   codespell:

pyro/compressible/unsplit_fluxes.py

@@ -257,7 +257,7 @@ def apply_source_terms(U_xl, U_xr, U_yl, U_yr,
         The data object containing the grid and advective scalar that
         we are advecting.
     my_aux : CellCenterData2d object
-        The data object that carries auxillary quantities which we need
+        The data object that carries auxiliary quantities which we need
         to fill in the ghost cells.
     rp : RuntimeParameters object
         The runtime parameters for the simulation