fix(build): remove temporary replace directive for external plugins

External plugins now reference pkg/plugin v0.1.19 directly.

Author: JeroenSoeters

Makefile

@@ -74,16 +74,10 @@ fetch-external-plugins:
 	fi
 
 ## build-external-plugins: Build all external plugins
-## Uses a go.mod replace directive so plugins build against the local pkg/plugin.
-## This ensures plugins stay compatible when plugin message types change.
 build-external-plugins: fetch-external-plugins
 	@for repo in $(EXTERNAL_PLUGIN_REPOS); do \
 		name=$$(basename $$repo .git); \
-		echo "Building $$name (with local pkg/plugin)..."; \
-		cd "$(PLUGINS_CACHE)/$$name" \
-			&& go mod edit -replace github.com/platform-engineering-labs/formae/pkg/plugin=$(CURDIR)/pkg/plugin \
-			&& go mod tidy \
-			&& cd "$(CURDIR)"; \
+		echo "Building $$name..."; \
 		$(MAKE) -C "$(PLUGINS_CACHE)/$$name" build; \
 	done