Ignore error from go clean -testcache

CI would fail with

make test TESTREPORT=test-results/go/results.xml
sed -e 's;@@gobin@@;/go/bin;g' < vault.hcl.in > vault.hcl
mkdir -p test-results/go/
go clean -testcache
go clean -testcache: open /tmp/go/cache/testexpire.txt: no such file or directory
make: *** [Makefile:29: test] Error 1

Author: Amey Bhide

Makefile

@@ -26,7 +26,7 @@ dev: build
 test: build
 	@test -n "$$SPLUNK_ADDR" || { echo 'warning: SPLUNK_ADDR not set, creating new Splunk instances.  This will be slow.'; }
 	mkdir -p $(dir $(TESTREPORT))
-	go clean -testcache
+	go clean -testcache || true
 	gotestsum --junitfile $(TESTREPORT) --format standard-verbose -- -cover -v ./...
 
 .PHONY: lint