Makefile: pin controller-gen binary to go 1.21

Author: chrischdi

Makefile

@@ -983,7 +983,8 @@ $(IMPORT_BOSS_BIN): $(IMPORT_BOSS)
 $(RELEASE_NOTES_BIN): $(RELEASE_NOTES) ## Build a local copy of release-notes.
 
 $(CONTROLLER_GEN): # Build controller-gen.
-	GOBIN=$(TOOLS_BIN_DIR) $(GO_INSTALL) $(CONTROLLER_GEN_PKG) $(CONTROLLER_GEN_BIN) $(CONTROLLER_GEN_VER)
+	# controller-gen 0.13 cannot be built with Go >= 1.22. We have to pin it to 1.21.
+	GOTOOLCHAIN=go1.21.11 GOBIN=$(TOOLS_BIN_DIR) $(GO_INSTALL) $(CONTROLLER_GEN_PKG) $(CONTROLLER_GEN_BIN) $(CONTROLLER_GEN_VER)
 
 ## We are forcing a rebuilt of conversion-gen via PHONY so that we're always using an up-to-date version.
 ## We can't use a versioned name for the binary, because that would be reflected in generated files.