Fix Muons configs

@Lara813 spotted a bug in the config for muons (for sure in [this one](https://github.com/cms-l1-dpg/Phase2-L1MenuTools/blob/main/configs/V44nano/object_performance/tkmuon_matching.yaml)), but maybe also in others.

The `reference_object` should use the `[`GenPart`](https://github.com/cms-l1-dpg/Phase2-L1MenuTools/blob/main/configs/V44nano/objects/GenPart.yaml):object:region` definition, as done, eg, in the [`electron_matching.yaml`](https://github.com/cms-l1-dpg/Phase2-L1MenuTools/blob/main/configs/V44nano/object_performance/electron_matching.yaml) config.

It should be:

```
TkMuonsMatchingBarrel:
sample: DYLL_M50
version: V44nano
match_test_to_ref: True
reference_object:
GenPart:reference_muon:barrel_muon: "pt"
test_objects:
# L1gmtMuon:default:barrel: "pt"
L1gmtTkMuon:default:barrel: "pt"
L1gmtTkMuon:VLoose:barrel: "pt"
L1gmtTkMuon:Loose:barrel: "pt"
L1gmtTkMuon:Medium:barrel: "pt"
L1gmtTkMuon:Tight:barrel: "pt"
xlabel: "Gen. $p_T$ (GeV)"
ylabel: "Matching Efficiency (barrel)"
binning:
min: 0
max: 100
step: 3
```

Also note that for muons in `GenPart` there are two `regions`: `barrel_muon` and `endcap_muon` that should be used, since also the `overlap` region should be used for muons.