xet: fix uploading to a branch with a slash in it (#1757)

https://huggingface.slack.com/archives/C02EMARJ65P/p1758197331824889

Author: coyotte508

packages/hub/src/utils/xetWriteToken.ts

@@ -47,8 +47,9 @@ export async function xetWriteToken(params: XetWriteTokenParams): Promise<{ acce
 
 	const promise = (async () => {
 		const resp = await (params.fetch ?? fetch)(
-			`${params.hubUrl}/api/${params.repo.type}s/${params.repo.name}/xet-write-token/${params.rev}` +
-				(params.isPullRequest ? "?create_pr=1" : ""),
+			`${params.hubUrl}/api/${params.repo.type}s/${params.repo.name}/xet-write-token/${encodeURIComponent(
+				params.rev
+			)}` + (params.isPullRequest ? "?create_pr=1" : ""),
 			{
 				headers: params.accessToken
 					? {