Update to base-compat-0.12.1

Changes in 0.12.1 [2021.10.30]
* Backport Solo to Data.Tuple.Compat when building with ghc-prim-0.7.0 or
  later

Changes in 0.12.0 [2021.08.29]
* Sync with base-4.16/GHC 9.2
* Data.Semigroup.Compat{.Repl} no longer re-exports the Option data type or
  the option function, as both have been removed in base-4.16.
* Backport readBin and showBin to Numeric.Compat
* Backport readBinP to Text.Read.Lex.Compat

(pho)