"Call is ambiguous" after an upgrade of the Unity version

Hi!

I am on a project at work and I upgraded the Unity version from 2018.3 to 2021.3.9f1. I have 6 error messages since then :

"Library\PackageCache\com.unity.timeline@1.7.1\Editor\Actions\IAction.cs(23,41): error CS0121: The call is ambiguous between the following methods or properties: 'System.MissingExtensions.GetCustomAttribute<T>(System.Reflection.MemberInfo, bool)' and 'System.Reflection.CustomAttributeExtensions.GetCustomAttribute<T>(System.Reflection.MemberInfo, bool)'"

I just have the issue witht the Timeline package. Everything else is fine.

My manifest :

Spoiler: Manifest

{
"dependencies": {
"com.unity.2d.sprite": "1.0.0",
"com.unity.2d.tilemap": "1.0.0",
"com.unity.analytics": "3.6.12",
"com.unity.ide.rider": "3.0.15",
"com.unity.ide.visualstudio": "2.0.16",
"com.unity.ide.vscode": "1.2.5",
"com.unity.recorder": "3.0.3",
"com.unity.test-framework": "1.1.31",
"com.unity.textmeshpro": "3.0.6",
"com.unity.timeline": "1.7.1",
"com.unity.ugui": "1.0.0",
"com.unity.vectorgraphics": "2.0.0-preview.20",
"com.unity.xr.legacyinputhelpers": "2.1.10",
"com.unity.modules.ai": "1.0.0",
"com.unity.modules.androidjni": "1.0.0",
"com.unity.modules.animation": "1.0.0",
"com.unity.modules.assetbundle": "1.0.0",
"com.unity.modules.audio": "1.0.0",
"com.unity.modules.cloth": "1.0.0",
"com.unity.modules.director": "1.0.0",
"com.unity.modules.imageconversion": "1.0.0",
"com.unity.modules.imgui": "1.0.0",
"com.unity.modules.jsonserialize": "1.0.0",
"com.unity.modules.particlesystem": "1.0.0",
"com.unity.modules.physics": "1.0.0",
"com.unity.modules.physics2d": "1.0.0",
"com.unity.modules.screencapture": "1.0.0",
"com.unity.modules.terrain": "1.0.0",
"com.unity.modules.terrainphysics": "1.0.0",
"com.unity.modules.tilemap": "1.0.0",
"com.unity.modules.ui": "1.0.0",
"com.unity.modules.uielements": "1.0.0",
"com.unity.modules.umbra": "1.0.0",
"com.unity.modules.unityanalytics": "1.0.0",
"com.unity.modules.unitywebrequest": "1.0.0",
"com.unity.modules.unitywebrequestassetbundle": "1.0.0",
"com.unity.modules.unitywebrequestaudio": "1.0.0",
"com.unity.modules.unitywebrequesttexture": "1.0.0",
"com.unity.modules.unitywebrequestwww": "1.0.0",
"com.unity.modules.vehicles": "1.0.0",
"com.unity.modules.video": "1.0.0",
"com.unity.modules.vr": "1.0.0",
"com.unity.modules.wind": "1.0.0",
"com.unity.modules.xr": "1.0.0"
}
}

I tried upgraded the package from 1.6.4 to 1.7.1 but nothing changed. I deleted the Library folder so that he regenerates the PackageCache files but the error messages are still there. I basically followed this thread : https://forum.unity.com/threads/timeline-in-2020-3-3f1-contains-errors.1095583/ but nothing worked. I can't afford to create a new project.

We need to release our Android build soon and I had to upgrade since Google Play Store needs to target API 31 from November 2022 and I could not do it from Unity 2018.3...