Revert "gnu: ghc-base-compat: Update to 0.10.4."

This reverts commit 0fa2c552fc.

We may not upgrade base-compat at this point because we haven't upgraded the
default GHC yet.

gnu/packages/haskell.scm

@@ -4231,7 +4231,7 @@ system.")
 (define-public ghc-base-compat
   (package
     (name "ghc-base-compat")
-    (version "0.10.4")
+    (version "0.9.3")
     (source
      (origin
        (method url-fetch)
@@ -4241,7 +4241,7 @@ system.")
              ".tar.gz"))
        (sha256
         (base32
-         "0ksp990gxs731mq19rzbxrbs43nazfljjc8krlx5bjqblw3kfs8d"))))
+         "0452l6zf6fjhy4kxqwv6i6hhg6yfx4wcg450k3axpyj30l7jnq3x"))))
     (build-system haskell-build-system)
     (native-inputs
      `(("ghc-quickcheck" ,ghc-quickcheck)