chore(composer): Make top-level data classes internal

As these classes were just introduced recently in 543de7b, do not mark
the change as breaking. Also make related helper functions internal to
not expose implementation details to the public API.

Signed-off-by: Sebastian Schuberth <sebastian@doubleopen.org>

plugins/package-managers/composer/src/main/kotlin/Model.kt

@@ -26,14 +26,14 @@ import com.fasterxml.jackson.module.kotlin.readValue
 import org.ossreviewtoolkit.model.jsonMapper
 
 @JsonIgnoreProperties(ignoreUnknown = true)
-data class Lockfile(
+internal data class Lockfile(
     val packages: List<PackageInfo> = emptyList(),
     @JsonProperty("packages-dev")
     val packagesDev: List<PackageInfo> = emptyList()
 )
 
 @JsonIgnoreProperties(ignoreUnknown = true)
-data class PackageInfo(
+internal data class PackageInfo(
     val name: String?,
     // See https://getcomposer.org/doc/04-schema.md#version.
     val version: String?,
@@ -73,6 +73,6 @@ data class PackageInfo(
     )
 }
 
-fun parseLockfile(json: String): Lockfile = jsonMapper.readValue<Lockfile>(json)
+internal fun parseLockfile(json: String): Lockfile = jsonMapper.readValue<Lockfile>(json)
 
-fun parsePackageInfo(json: String): PackageInfo = jsonMapper.readValue<PackageInfo>(json)
+internal fun parsePackageInfo(json: String): PackageInfo = jsonMapper.readValue<PackageInfo>(json)