fix: Android flavors starting with uppercase letters are incorrectly parsed

[bryanoltman]

With a gradle file like:

productFlavors {
        RJ {
            dimension "flavor-type"
            applicationId "br.com.brasizza.marcus.guia_rj"
            resValue "string", "app_name", "Guia do Rio de janeiro"
        }
        SP {
            dimension "flavor-type"
            applicationId "br.com.brasizza.marcus.guia_sp"
            resValue "string", "app_name", "Guia de São Paulo"
        }
    }

shorebird init recognized these flavors as

✓ 2 product flavors detected: (13.8s)
  - rJ
  - sP

See https://discord.com/channels/1030243211995791380/1237476178055397459