feat: add the --version CLI option to print the version information

src/PostgREST/CLI.hs

@@ -80,7 +80,7 @@ readCLIShowHelp =
   where
     prefs = O.prefs $ O.showHelpOnError <> O.showHelpOnEmpty
     opts = O.info parser $ O.fullDesc <> progDesc
-    parser = O.helper <*> exampleParser <*> cliParser
+    parser = O.helper <*> versionFlag <*> exampleParser <*> cliParser
 
     progDesc =
       O.progDesc $
@@ -88,6 +88,12 @@ readCLIShowHelp =
         <> BS.unpack prettyVersion
         <> " / create a REST API to an existing Postgres database"
 
+    versionFlag =
+      O.infoOption ("PostgREST " <> BS.unpack prettyVersion) $
+        O.long "version"
+        <> O.short 'v'
+        <> O.help "Show the version information"
+
     exampleParser =
       O.infoOption exampleConfigFile $
         O.long "example"