chore: satisfy Bioconda lint metadata

[ehsanestaji]

Carry back the Bioconda lint metadata required by the upstream recipe check.

Changes:

• Add run_exports with max_pin="x.x" for the pre-1.0 fastaguard package.
• Add {{ stdlib('c') }} because the recipe requests compilers.
• Extend release metadata tests so the starter recipe stays aligned with Bioconda lint expectations.

Verification:

• python3 -m unittest tests.python.test_release_metadata -v
• python3 -m unittest discover tests/python -v
• git diff --check