Fix use_bioconductor = FALSE still hitting bioconductor.org on R 4.5+

Fixes https://github.com/r-lib/pak/issues/851 Fixes the behavior where setting options(pkg.use_bioconductor = FALSE) still causes a network request to https://bioconductor.org/config.yaml, breaking installations in corporate firewall environments. What was happening: Inside cmc__get_repos(), bioconductor$get_repos() was called unconditionally to classify user-configured repos as "bioc" vs "cranlike" — regardless of the bioc argument. On R <= 4.4 this was harmless because the hardcoded R→Bioc version map returns immediately. On R 4.5+, the version isn't in that map (intentionally), so it falls through to a live HTTP fetch of the Bioconductor config YAML — which fails behind a firewall even when the user explicitly opted out of Bioconductor. The fix: One line. When bioc = FALSE, no Bioconductor code is touched. The downstream %in% check still works correctly — it just returns all FALSE, classifying everything as "cranlike" as expected.