chore(ci): DSPX-1424 Enforce minimum buf version (#2641)

### Proposed Changes

* Enforce minimum `buf` version

### Checklist

- [ ] I have added or updated unit tests
- [ ] I have added or updated integration tests (if appropriate)
- [ ] I have added or updated documentation

### Testing Instructions

Author: b-long

.github/workflows/checks.yaml

@@ -480,6 +480,7 @@ jobs:
       - uses: bufbuild/buf-setup-action@a47c93e0b1648d5651a065437926377d060baa99 # v1.50.0
         with:
           github_token: ${{ github.token }}
+          version: "1.56.0"
       - uses: bufbuild/buf-lint-action@06f9dd823d873146471cfaaf108a993fe00e5325 # v1.1.1
         with:
           input: service

Makefile

@@ -5,6 +5,7 @@
 
 MODS=protocol/go lib/ocrypto lib/fixtures lib/flattening lib/identifier sdk service examples
 HAND_MODS=lib/ocrypto lib/fixtures lib/flattening lib/identifier sdk service examples
+REQUIRED_BUF_VERSION=1.56.0
 
 ROOT_DIR:=$(shell dirname $(realpath $(firstword $(MAKEFILE_LIST))))
 
@@ -17,6 +18,12 @@ all: toolcheck clean build lint license test
 toolcheck:
 	@echo "Checking for required tools..."
 	@which buf > /dev/null || (echo "buf not found, please install it from https://docs.buf.build/installation" && exit 1)
+	@BUF_VERSION=$$(buf --version | head -n 1 | awk '{print $$1}'); \
+	if [ "$$(printf '%s\n' '$(REQUIRED_BUF_VERSION)' "$$BUF_VERSION" | sort -V | head -n 1)" != "$(REQUIRED_BUF_VERSION)" ]; then \
+		echo "Error: buf version $(REQUIRED_BUF_VERSION) or later is required, but found $$BUF_VERSION."; \
+		echo "Please upgrade buf. See https://docs.buf.build/installation for instructions."; \
+		exit 1; \
+	fi
 	@which golangci-lint > /dev/null || (echo "golangci-lint not found, run  'go install github.com/golangci/golangci-lint/cmd/[email protected]'" && exit 1)
 	@which protoc-gen-doc > /dev/null || (echo "protoc-gen-doc not found, run 'go install github.com/pseudomuto/protoc-gen-doc/cmd/[email protected]'" && exit 1)
 	@which protoc-gen-connect-openapi > /dev/null || (echo "protoc-gen-connect-openapi not found, run 'go install github.com/sudorandom/[email protected]'" && exit 1)