SyntaxError in file, Unexpected keyword temp in rule definition

[LilyAndrews6]

When I run:

snakemake --use-conda -s cellect-ldsc.snakefile --configfile config.yml --conda-frontend conda

I get the following error:

SyntaxError in file /CELLECT/cellect-ldsc.snakefile, line 298:
Unexpected keyword temp in rule definition (cellect-ldsc.snakefile, line 298)

This is line 298 the error message is referring to:

temp("{BASE_OUTPUT_DIR}/precomputation/{run_prefix}/{run_prefix}.COMBINED_ANNOT.{chromosome}.l2.ldscore.gz"), # TEMP FILE

I am using:
snakemake -v
8.6.0

Has anyone else had this issue or know a way to resolve it? Thanks for your help.