;dev: build everything with at least GHC2021 language extensions by default

Previously everything was built with hpack's default, which is Haskell2010.

hledger-lib/package.yaml

@@ -95,6 +95,8 @@ dependencies:
 - extra >=1.7.11
 - Glob >= 0.9
 
+language: GHC2021
+
 ghc-options:
 - -Wall
 - -Wno-incomplete-uni-patterns

hledger-ui/package.yaml

@@ -58,6 +58,8 @@ flags:
 
 cpp-options: -DVERSION="1.50.99"
 
+language: GHC2021
+
 ghc-options:
 - -Wall
 - -Wno-incomplete-uni-patterns

hledger-web/package.yaml

@@ -68,6 +68,8 @@ flags:
 #    default: false
 #    manual:  true
 
+language: GHC2021
+
 ghc-options:
 - -Wall
 # not included in -Wall:

hledger/package.yaml

@@ -104,6 +104,8 @@ flags:
 #    default: false
 #    manual:  true
 
+language: GHC2021
+
 ghc-options:
 - -Wall
 - -Wno-incomplete-uni-patterns