build: strip leading bin dir for tar archives

Signed-off-by: Nico Braun <rainbowstack@gmail.com>

Makefile

@@ -88,7 +88,7 @@ image-build: ## Build the images with VERSION as tag. Passes BUILDX_FLAGS to bui
 .PHONY: artifacts
 artifacts: bin/kustomize build ## Create all release artifacts and put the in .dist/
 	mkdir -p .dist && rm -rf .dist/*
-	$(foreach binary,$(wildcard bin/kobold*),tar -czf .dist/$(notdir $(binary)).$(GOOS)-$(GOARCH).tgz $(binary);)
+	$(foreach binary,$(wildcard bin/kobold*),tar -C bin -czf .dist/$(notdir $(binary)).$(GOOS)-$(GOARCH).tgz $(notdir $(binary));)
 	bin/kustomize build manifests/dist/ -o .dist/kobold.manifests.yaml
 	cp assets/schema.json .dist/kobold.schema.json
 	$(MAKE) image-build BUILDX_FLAGS='--set *.attest=type=sbom \