Makefile: allow warnings for installing cross

Signed-off-by: Jiaxiao (mossaka) Zhou <[email protected]>

Author: Mossaka

Makefile

@@ -147,7 +147,7 @@ tests/clean:
 # pin cross to a specific commit to avoid breaking changes
 .PHONY: install-cross install-k3d check-bins pod-status-check setup
 install-cross:
-	@if [ -z $$(which cross) ]; then cargo install cross --git https://github.com/cross-rs/cross --rev 49338b18fdb82dedb2a813664e2e565ca73e2047; fi
+	@if [ -z $$(which cross) ]; then RUSTFLAGS="-A warnings" cargo install cross --git https://github.com/cross-rs/cross --rev 49338b18fdb82dedb2a813664e2e565ca73e2047; fi
 	@cross -V 2>/dev/null | grep 49338b1 || echo "WARN: unsupported version of cross found. Building containerd-shim-spin requires specific version of cross.\n\nPlease uninstall and run make install-cross to install the supported version."
 
 install-k3d: