qcscine/molassembler: Release 2.0.0

Changes:

• Cleaving graphs always returns Cleave object including ComponentMap
• Changed C++ standard from C++14 to C++17
• BondStereopermutator update on atom deletion
• Dependency handling for Boost versions >1.70
• BondStereoPermutator determination on eta bonds
• Nitrogen thermalization in cyclic systems
• Feasible stereopermutations consistency between serialization and deserialization
• The gradient target for the conformer optimization is now passed correctly