add3prf.py: Update value for crates.io identifier

According to go/thirdparty/metadata#identifier

> The identifier field is used to enable this functionality. The type
> field should correspond to one of OSV's defined ecosystems or one of the
> google internal types. Select the identifier type which matches where
> the package was obtained before importing to Piper. The value should be
> the name of the package as defined within that ecosystem - see the
> examples below.

The OSV's defined ecosystem is here:
https://ossf.github.io/osv-schema/#affectedpackage-field

For "crates.io" the table says the name field should be the crate name.

Bug: 322046255
Test: N/A
Change-Id: I3647614f4e9a5157743bf907366cbeaf0c4ed74a
diff --git a/scripts/add3prf.py b/scripts/add3prf.py
index 6c8185a..ab1dff5 100755
--- a/scripts/add3prf.py
+++ b/scripts/add3prf.py
@@ -74,7 +74,7 @@
 third_party {{
   identifier {{
     type: "crates.io"
-    value: "https://crates.io/crates/{name}"
+    value: "{name}"
   }}
   identifier {{
     type: "Archive"