Update dependabot config (#1100)

Add check for github-actions.
Add missing examples and SDK go.mod
Remove redundant comments.
Change check to be weekly on Sunday to reduce load and churn.
Sort alphanumerically.
Add check to Makefile to ensure if there is a `go.mod` file there is a dependabot entry for that directory.

Makefile

@@ -57,7 +57,7 @@ $(TOOLS_DIR)/gojq: $(TOOLS_MOD_DIR)/go.mod $(TOOLS_MOD_DIR)/go.sum $(TOOLS_MOD_D
 	cd $(TOOLS_MOD_DIR) && \
 	go build -o $(TOOLS_DIR)/gojq github.com/itchyny/gojq/cmd/gojq
 
-precommit: generate build lint examples test
+precommit: dependabot-check license-check generate build lint examples test
 
 .PHONY: test-with-coverage
 test-with-coverage:
@@ -74,7 +74,7 @@ test-with-coverage:
 
 
 .PHONY: ci
-ci: precommit check-clean-work-tree license-check test-with-coverage test-386
+ci: precommit check-clean-work-tree test-with-coverage test-386
 
 .PHONY: check-clean-work-tree
 check-clean-work-tree:
@@ -155,3 +155,16 @@ license-check:
 	           echo "license header checking failed:"; echo "$${licRes}"; \
 	           exit 1; \
 	   fi
+
+.PHONY: dependabot-check
+dependabot-check:
+	@result=$$( \
+		for f in $$( find -type f -name go.mod -exec dirname {} \; | sed 's/^.\/\?/\//' ); \
+			do grep -q "$$f" .github/dependabot.yml \
+			|| echo "$$f"; \
+		done; \
+	); \
+	if [ -n "$$result" ]; then \
+		echo "missing go.mod dependabot check:"; echo "$$result"; \
+		exit 1; \
+	fi