v1.1.3

Introduce GO_TEST_EXEC to allow overriding go test command. (#939)

Introduced the following variable to the `Makefile`:

```
GO_TEST_EXEC := go test
```

That variable can be customized to run the tests with a different runner
or wrapper of `go test`. For instance, locally, I'm overriding that with
a library _unhappily_ named [gotest](https://github.com/rakyll/gotest)
that allows color output and makes reading test errors easier. That tool
can be added to the project using `mise`:

```
[tools]
...
'go:github.com/rakyll/gotest' = 'latest'
```