Add bounds for base in hls-test-utils (backport #1791) (#1793)

* Add bounds for base in hls-test-utils (#1791)

(cherry picked from commit 98fa0fc)

# Conflicts:
#	hls-test-utils/hls-test-utils.cabal

* Fix conflict

Co-authored-by: Potato Hatsue <1793913507@qq.com>

Author: mergify[bot]

hls-test-utils/hls-test-utils.cabal

@@ -5,9 +5,7 @@ synopsis:      Utilities used in the tests of Haskell Language Server
 description:
   Please see the README on GitHub at <https://github.com/haskell/haskell-language-server#readme>
 
-homepage:
-  https://github.com/haskell/haskell-language-server#readme
-
+homepage:      https://github.com/haskell/haskell-language-server#readme
 bug-reports:   https://github.com/haskell/haskell-language-server/issues
 license:       Apache-2.0
 license-file:  LICENSE
@@ -35,7 +33,7 @@ library
   build-depends:
     , aeson
     , async
-    , base
+    , base                    >=4.12     && <5
     , blaze-markup
     , bytestring
     , containers