Unstable Debian repository doesn't install latest snapshot
First of all, thanks a ton for Kaitai Struct!

It looks like the unstable Debian repository isn't installing the latest available snapshot by default.

Using the following steps:

```bash
apt-key adv --keyserver keyserver.ubuntu.com --recv 379CE192D401AB61 && \
    echo "deb https://dl.bintray.com/kaitai-io/debian_unstable jessie main" \
        | tee /etc/apt/sources.list.d/kaitai.list && \
    apt-get update && \
    apt-get install -y kaitai-struct-compiler
```

And running the following:

```bash
$ kaitai-struct-compiler --version
```

I get `0.9-SNAPSHOT522603588` instead of `0.9-SNAPSHOT20200607.053216.a0d7f531`, which is what I expect.

I'm currently attempting to install the latter explicitly via `apt-get install -y kaitai-struct-compiler=0.9-SNAPSHOT20200607.053216.a0d7f531`; will report on the effects.