api: require servant-server 0.10+ to fix compilation warning

hledger-api/hledger-api.cabal

@@ -58,7 +58,7 @@ executable hledger-api
     , microlens >=0.4 && <0.5
     , microlens-platform >=0.2.3.1 && <0.4
     , safe
-    , servant-server
+    , servant-server >= 0.10
     , servant-swagger
     , swagger2
     , text

hledger-api/hledger-api.hs

@@ -141,7 +141,7 @@ hledgerApiApp staticdir j = Servant.serve api server
       :<|> accounttransactionsH
       )
       --
-      :<|> serveDirectory staticdir
+      :<|> serveDirectoryFileServer staticdir
       where
         accountnamesH = return $ journalAccountNames j
         transactionsH = return $ jtxns j

hledger-api/package.yaml

@@ -39,7 +39,7 @@ dependencies:
 - microlens >=0.4 && <0.5
 - microlens-platform >=0.2.3.1 && <0.4
 - safe
-- servant-server
+- servant-server >= 0.10
 - servant-swagger
 - swagger2
 - text