Ignore missing brotli wheel for RISC-V.

With this last step, it is now possible to `gclient sync` on a Linux RV64 host.

Bug: https://issues.chromium.org/issues/40153066
Bug: https://issues.chromium.org/issues/359654093
Bug: https://github.com/dart-lang/sdk/issues/48545
Change-Id: I38b74e26e5692b39b48a38c0e0c482ea1d0ad7ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5786164
Commit-Queue: Ryan Macnak <rmacnak@google.com>
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>

.vpython3

@@ -50,6 +50,8 @@ wheel: <
 wheel: <
   name: "infra/python/wheels/brotli/${vpython_platform}"
   version: "version:1.0.9"
+  # TODO(crbug.com/359654093): Setup RISC-V wheel builder
+  not_match_tag: {python: "cp311", abi: "cp311", platform: "linux_riscv64"},
 >
 
 # Used by: