Resolve "release v1.4.0"

Closes #317 (closed)

mlair/helpers/filter.py

@@ -466,6 +466,7 @@ class ClimateFIRFilter:
 
             # select only values at tmp dimension 0 at each point in time
             coll.append(filt.sel({new_dim: 0}, drop=True))
+            gc.collect()
 
         logging.info(f"{data.coords['Stations'].values[0]}: concat all variables")
         res = xr.concat(coll, var_dim)