vim-patch:9.1.0486: filetype: Snakemake files are not recognized

Problem:  filetype: Snakemake files are not recognized
Solution: Detect '*.smk' and Snakefile files as snakemake filetype
          (Riley Bruins)

See:
https://snakemake.readthedocs.io/en/stable/snakefiles/deployment.html#distribution-and-reproducibility

closes: vim/vim#14992

82a579e15a

Co-authored-by: Riley Bruins <ribru17@hotmail.com>
Co-authored-by: zeertzjq <zeertzjq@outlook.com>

test/old/testdir/test_filetype.vim

@@ -670,6 +670,7 @@ func s:GetFilenameChecks() abort
     \ 'smith': ['file.smt', 'file.smith'],
     \ 'smithy': ['file.smithy'],
     \ 'sml': ['file.sml'],
+    \ 'snakemake': ['file.smk', 'Snakefile'],
     \ 'snobol4': ['file.sno', 'file.spt'],
     \ 'solidity': ['file.sol'],
     \ 'solution': ['file.sln'],