tests/int/spec.bats: fix for go 1.16

go 1.16 has GO111MODULE=on by default, and since runtime-spec/schema
does not come with go.mod, it complains:

> runtime-spec/schema/validate.go:10:2: no required module provides package github.com/xeipuuv/gojsonschema: working directory is not part of a module

Use GO111MODULE=auto as a workaround.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

tests/integration/spec.bats

@@ -33,8 +33,8 @@ function teardown() {
 	SCHEMA='runtime-spec/schema/config-schema.json'
 	[ -e "$SCHEMA" ]
 
-	go get github.com/xeipuuv/gojsonschema
-	go build runtime-spec/schema/validate.go
+	GO111MODULE=auto go get github.com/xeipuuv/gojsonschema
+	GO111MODULE=auto go build runtime-spec/schema/validate.go
 
 	./validate "$SCHEMA" config.json
 }