Make the current `base` buildable with GHC 9.14

Wolfgang Jeltschrequested to merge
wip/jeltsch/base-buildable-with-ghc-9-14 into master

In the medium run, we’d like to provide base versions that work with different versions of GHC each. As a first step, !16035 (closed) made the current base buildable with GHC 10.0. This contribution makes it buildable with GHC 9.14.

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