fix: "no release" is the lowest priority

[nweajoseph]

prior to this commit, using a custom analysis rule that set release to false, for example:

[
    {type: 'fix', scope: 'frontend', release: 'patch'},
    {type: 'fix', scope: '*', release: false} // <----- this should NOT override 'patch'
]

would skip the release matching commits, even though another rule matches them with a higher release value. that is to say: this commit codifies false or null release values as the "lowest" release value, making it possible to treat "no release" the same way we treat all other release values, instead of treating it as a special exception. the primary use-case for this change is more granular control over commit analysis when using scopes

BREAKING CHANGE: release: false will not override other matching release rules of higher priority