Migration changes the SQLDelight dialect version

[1gravity]

• [x] I have read the guidelines for submitting issues

🐛 Describe the bug

when running a a migration this:

sqldelight {
    database("SudokuDatabase") {
        packageName = "com.mydomain.myapp"
        sourceFolders = listOf("sqldelight")
        dialect = "sqlite:3.25"
    }
}

is changed to:

sqldelight {
    database("SudokuDatabase") {
        packageName = "com.mydomain.myapp"
        sourceFolders = listOf("sqldelight")
        dialect = "sqlite:3.25:_"
    }
}

The build obviously fails afterwards.

⚠️ Current behavior

Migrations converts dialect = "sqlite:3.25" to dialect = "sqlite:3.25:_"

✅ Expected behavior

Migrations doesn't convert dialect = "sqlite:3.25"

💣 Steps to reproduce

Add SQLDelight to an app and run a migration.

[LouisCAD]

@jmfayard Relates to #470