message: Fix release year 2020 -> 2021
diff: # CHANGELOG
  -## 0.13.2 (2020-01-14)
  +## 0.13.2 (2021-01-14)
  - cosmwasm-vm: Update Wasmer to 1.0.1.
  -## 0.13.1 (2020-01-12)
  +## 0.13.1 (2021-01-12)
  **cosmwasm-std**
  `cosmwasm_std::create_entry_points_with_migration!(contract)`. Both ways are
  supported in the 0.13 series.
  -## 0.13.0 (2020-01-06)
  +## 0.13.0 (2021-01-06)
  **all**
  