Minors are not backward compatible

Tsup 6.5.0 and 6.7.0, are not backwards compatible. Lack of compatibility has been spotted in a following way:

package.json
```
"devDependencies": {
"tsup": "^6.5.0",
},
scripts: {
"build": "tsup --minify=true",
}
```
6.7.0 statisfies "^". Tsup 6.7.0 expects `tsup --minify` as a command, otherwise you get an error that minify is not a boolean.

**Expected behavior**
Both commands should work when versions are "^" compatible.

The issue can be closed, however it would be lovely to keep semantic versioning in the future :-)