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