Record conda checksum for v3.1.0

The v3.1.0 source archive only exists once the tag is pushed, so the recipe
carried a placeholder through the release PR. Fetched from the published tag
with `python3 scripts/release.py 3.1.0 --fetch-conda-sha256`.

Next: update conda-forge/vcf-rdfizer-feedstock from conda-recipe/meta.yaml.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: ecrum19

conda-recipe/meta.yaml

@@ -7,7 +7,7 @@ package:
 
 source:
   url: https://github.com/ecrum19/VCF-RDFizer/archive/refs/tags/v{{ version }}.tar.gz
-  sha256: REPLACE_WITH_GITHUB_TARBALL_SHA256
+  sha256: 0fa8dfd1e4d35c39594a5183a7c36569cee5857974f69b6db746dd705fae03ca
 
 build:
   noarch: python