It’s really useful to format your code with triple backticks ``` to make it legible.
In short, you have MCMCDiagnosticTools in your environment which restricts MCMCChains to versions <=4.14, and you also have Turing in your environment which is restricted to >=0.23.2 by CRRao. Turing@0.23.2 does not allow MCMCChains below version 5 though, so the environment cannot be resolved.
It also looks like you are installing all your packages in the default environment - don’t do this, work with project specific environments instead to minimise incompatibilities like this.