fix: filter prereleases in version range matching in _select_release_by_version

When using version range operators (>=, >, <, <=) with prerelease=False,
prerelease releases were not being filtered out, causing them to be
incorrectly selected over stable releases.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: mballance

src/ivpm/pkg_types/package_gh_rls.py

@@ -359,6 +359,8 @@ def _select_release_by_version(self, releases):
                 rv = self._parse_version_tuple(r.get("tag_name",""))
                 if rv is None:
                     continue
+                if r.get("prerelease") and not self.prerelease:
+                    continue
                 c = self._cmp_versions(rv, tgt)
                 ok = False
                 if op == ">": ok = c > 0