Verify downloads with astral-sh/versions checksums (#1033)

`setup-uv` currently ignores the `sha256` supplied by the default
`astral-sh/versions` manifest when a selected artifact is newer than its
bundled checksum table, allowing that download to proceed without
validation. Use the manifest checksum as a fallback after explicit and
bundled checksums, and reject manifest entries that do not provide one.
This preserves the stronger pinned hashes for known releases while
verifying newer releases without requiring an action update. Part of
#1032.

---------

Co-authored-by: Zanie Blue <contact@zanie.dev>
Co-authored-by: William Woodruff <william@yossarian.net>
Co-authored-by: Kevin Stillhammer <kevin.stillhammer@gmail.com>

dist/setup/index.cjs

@@ -99730,15 +99730,20 @@ var known_checksums_default = {
 var KNOWN_CHECKSUMS = known_checksums_default;
 
 // src/download/checksum/checksum.ts
-async function validateChecksum(checksum, downloadPath, arch3, platform2, version3) {
+async function validateChecksum(checksum, downloadPath, arch3, platform2, version3, manifestChecksum) {
   const key = `${arch3}-${platform2}-${version3}`;
   const hasProvidedChecksum = checksum !== void 0 && checksum !== "";
-  const checksumToUse = hasProvidedChecksum ? checksum : KNOWN_CHECKSUMS[key];
+  const knownChecksum = KNOWN_CHECKSUMS[key];
+  const hasManifestChecksum = manifestChecksum !== void 0 && manifestChecksum !== "";
+  const checksumToUse = hasProvidedChecksum ? checksum : knownChecksum ?? (hasManifestChecksum ? manifestChecksum : void 0);
   if (checksumToUse === void 0) {
+    if (manifestChecksum !== void 0) {
+      throw new Error(`No checksum found for ${key} in manifest.`);
+    }
     debug(`No checksum found for ${key}.`);
     return;
   }
-  const checksumSource = hasProvidedChecksum ? "provided checksum" : `KNOWN_CHECKSUMS entry for ${key}`;
+  const checksumSource = hasProvidedChecksum ? "provided checksum" : knownChecksum !== void 0 ? `KNOWN_CHECKSUMS entry for ${key}` : "manifest checksum";
   debug(`Validating checksum using ${checksumSource}.`);
   const isValid = await validateFileCheckSum(downloadPath, checksumToUse);
   if (!isValid) {
@@ -101656,6 +101661,7 @@ async function downloadVersion(platform2, arch3, version3, checksum, githubToken
     );
   }
   const resolvedChecksum = manifestUrl === void 0 ? checksum : resolveChecksum(checksum, artifact.checksum);
+  const manifestChecksum = artifact.checksum;
   const mirrorUrl = downloadFromAstralMirror ? rewriteToMirror(artifact.downloadUrl) : void 0;
   const downloadUrl = mirrorUrl ?? artifact.downloadUrl;
   try {
@@ -101666,6 +101672,7 @@ async function downloadVersion(platform2, arch3, version3, checksum, githubToken
       arch3,
       version3,
       resolvedChecksum,
+      manifestChecksum,
       githubTokenForUrl(downloadUrl, githubToken)
     );
   } catch (err) {
@@ -101682,6 +101689,7 @@ async function downloadVersion(platform2, arch3, version3, checksum, githubToken
       arch3,
       version3,
       resolvedChecksum,
+      manifestChecksum,
       githubTokenForUrl(artifact.downloadUrl, githubToken)
     );
   }
@@ -101699,14 +101707,21 @@ function githubTokenForUrl(downloadUrl, githubToken) {
     return void 0;
   }
 }
-async function downloadArtifact(downloadUrl, artifactName, platform2, arch3, version3, checksum, githubToken) {
+async function downloadArtifact(downloadUrl, artifactName, platform2, arch3, version3, checksum, manifestChecksum, githubToken) {
   info2(`Downloading uv from "${downloadUrl}" ...`);
   const downloadPath = await downloadTool(
     downloadUrl,
     void 0,
     githubToken
   );
-  await validateChecksum(checksum, downloadPath, arch3, platform2, version3);
+  await validateChecksum(
+    checksum,
+    downloadPath,
+    arch3,
+    platform2,
+    version3,
+    manifestChecksum
+  );
   let uvDir;
   if (platform2 === "pc-windows-msvc") {
     try {