Release of version 2.0

Dependencies

• Coq: v8.13.2
• MathComp: 1.12.0
• Coquelicot: 3.1.0

Main changes from version 1.0 to version 2.0

• Inequalities ">" and ">=" are replaced with "<" and "<=" (advice from ZulipChat).
• The force of mortality is formalized.
• Notations "δ", "ω" are changed to "\δ", "\ω" respectively.
• Some basic lemmas are taken in the "auto" tactic by "Hint Resolve".
• Generalized the frequency of payments in Premium.v. and Reserve.v.
• The continuous payment case is newly formalized.