Update to pypsa 0.26.2

[ClaraBuettner]

Check arguments:

• [x] ehv clustering
• [x] k means (gas and AC)
• [x] k medoid-dijkstra (gas and AC)
• [x] skip snapshots
• [x] snapshot clustering
• [x] segmentation
• [x] temporal disaggregation
• [x] spatial disaggregation
• [x] foreign DC lines
• [x] capacities foreign countries
• [x] load shedding
• [x] lopf
• [x] pf

Plots might be checked in #685