Fix links in PyPI Simple Repository API page (#30594)

Thanks to @Zottelchen for looking into problem and proposing the fix.

Ref: https://github.com/astral-sh/uv/issues/3017 ,
https://peps.python.org/pep-0503/

This PR's change is from Zottelchen's work.

And I by the way rename the `$p` to `$pd` because `p` is used as
"package" in code, while `pd` is used as "package description".

----

Co-authored-by: Zottelchen

tests/integration/api_packages_pypi_test.go

@@ -164,7 +164,7 @@ func TestPackagePyPI(t *testing.T) {
 		nodes := htmlDoc.doc.Find("a").Nodes
 		assert.Len(t, nodes, 2)
 
-		hrefMatcher := regexp.MustCompile(fmt.Sprintf(`%s/files/%s/%s/test\..+#sha256-%s`, root, regexp.QuoteMeta(packageName), regexp.QuoteMeta(packageVersion), hashSHA256))
+		hrefMatcher := regexp.MustCompile(fmt.Sprintf(`%s/files/%s/%s/test\..+#sha256=%s`, root, regexp.QuoteMeta(packageName), regexp.QuoteMeta(packageVersion), hashSHA256))
 
 		for _, a := range nodes {
 			for _, att := range a.Attr {