libstore/filetransfer: Add HttpMethod::PUT

This got lost in f1968ea38e and
now we had incorrect logs that confused "downloading" when we were
in fact "uploading" things.

src/libstore/http-binary-cache-store.cc

@@ -141,7 +141,7 @@ void HttpBinaryCacheStore::upsertFile(
     uint64_t sizeHint)
 {
     auto req = makeRequest(path);
-
+    req.method = HttpMethod::PUT;
     auto data = StreamToSourceAdapter(istream).drain();
 
     auto compressionMethod = getCompressionMethod(path);