Fixed body parameter in github models

[tegorov]

I'm getting this error when trying to run Danger from CI (Github Actions):

kotlinx.serialization.json.internal.JsonDecodingException: Unexpected JSON token at offset 4707: Expected string or non-null literal
JSON input: .....h"
        },
        "body": null,
        "closed_by": nul.....
	at kotlinx.serialization.json.internal.JsonExceptionsKt.JsonDecodingException(JsonExceptions.kt:24)
	at kotlinx.serialization.json.internal.JsonExceptionsKt.JsonDecodingException(JsonExceptions.kt:32)
	at kotlinx.serialization.json.internal.JsonReader.fail(JsonReader.kt:333)
	at kotlinx.serialization.json.internal.JsonReader.takeString(JsonReader.kt:147)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeString(StreamingJsonDecoder.kt:210)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeStringElement(AbstractDecoder.kt:56)
	at systems.danger.kotlin.models.github.GitHubIssue$$serializer.deserialize(GitHub.kt:242)
	at systems.danger.kotlin.models.github.GitHubIssue$$serializer.deserialize(GitHub.kt:242)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:63)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:33)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeSerializableValue(AbstractDecoder.kt:41)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeSerializableElement(AbstractDecoder.kt:63)
	at systems.danger.kotlin.models.github.GitHub$$serializer.deserialize(GitHub.kt:13)
	at systems.danger.kotlin.models.github.GitHub$$serializer.deserialize(GitHub.kt:13)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:63)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:33)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeSerializableValue(AbstractDecoder.kt:41)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeNullableSerializableElement(AbstractDecoder.kt:72)
	at systems.danger.kotlin.models.danger.DangerDSL$$serializer.deserialize(DangerDSL.kt:14)
	at systems.danger.kotlin.models.danger.DangerDSL$$serializer.deserialize(DangerDSL.kt:14)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:63)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:33)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeSerializableValue(AbstractDecoder.kt:41)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeSerializableElement(AbstractDecoder.kt:63)
	at systems.danger.kotlin.models.danger.DSL$$serializer.deserialize(DangerDSL.kt:9)
	at systems.danger.kotlin.models.danger.DSL$$serializer.deserialize(DangerDSL.kt:9)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:63)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:33)
	at kotlinx.serialization.json.Json.decodeFromString(Json.kt:85)
	at systems.danger.kotlin.MainDangerRunner.<init>(MainDangerRunner.kt:124)
	at systems.danger.kotlin.MainScriptKt.Danger(MainScript.kt:44)
	at Dangerfile_df.<init>(Dangerfile.df.kts:39)

If a pull request is created through github api without body parameter, then body parameter will be null
For verification, I created pull request through github api: tegorov#1

[gianluz]

Thanks for the pull request!! could you please update the CHANGELOG.md with your PR?

[f-meloni]

After the CHANGELOG is updated for me is ready to go :)

Thank you!

[tegorov]

Thanks! I updated the changelog