revert filepath lower bound updates (#573)

Author: shayne-fletcher

ghc-lib-gen/src/Ghclibgen.hs

@@ -1226,14 +1226,14 @@ commonBuildDepends ghcFlavor =
             "containers >= 0.6.2.1 && < 0.8",
             "bytestring >= 0.11.4 && < 0.13",
             "time >= 1.4 && < 1.15",
-            "filepath >= 1.5 && < 1.6"
+            "filepath >= 1 && < 1.6"
           ]
       | ghcSeries ghcFlavor >= GHC_9_8 =
           [ "ghc-prim > 0.2 && < 0.12",
             "containers >= 0.6.2.1 && < 0.8",
             "bytestring >= 0.11.4 && < 0.13",
             "time >= 1.4 && < 1.15",
-            "filepath >= 1.5 && < 1.6"
+            "filepath >= 1 && < 1.6"
           ]
       | ghcSeries ghcFlavor >= GHC_9_6 =
           [ "ghc-prim > 0.2 && < 0.11",