ci: Fix triggering events and release actions

* Run CI only on pull requests, push to main and push
  to tags matching v*. This avoids running the CI more than
  once for a single user action
* Change pre-releases, which are now identified by a version
  number with 4 components (e.g., 1.1.1.1)
* Change how release artifacts are packaged, ensuring they
  are executable and compressed with xz

src/PostgREST/Version.hs

@@ -1,5 +1,4 @@
 {-# LANGUAGE TemplateHaskell #-}
-{-# OPTIONS_GHC -fno-warn-type-defaults #-}
 module PostgREST.Version
   ( docsVersion
   , prettyVersion
@@ -7,23 +6,36 @@ module PostgREST.Version
 
 import qualified Data.Text as T
 
-import Data.Version       (versionBranch)
+import Data.Version       (showVersion, versionBranch)
 import Development.GitRev (gitHash)
 import Paths_postgrest    (version)
 
 import Protolude
 
 
--- | User friendly version number
+-- | User friendly version number such as '1.1.1'.
+-- Pre-release versions are tagged as such, e.g., '1.1.1.1 (pre-release)'.
+-- If a git hash is available, it's added to the version, e.g., '1.1.1 (abcdef0)'.
 prettyVersion :: Text
 prettyVersion =
-  T.intercalate "." (map show $ versionBranch version) <> gitRev
+  T.pack (showVersion version) <> preRelease <> gitRev
   where
     gitRev =
-      if $(gitHash) == "UNKNOWN"
-        then mempty
-        else " (" <> T.take 7 $(gitHash) <> ")"
+      if $(gitHash) == ("UNKNOWN" :: Text) then
+        mempty
+      else
+        " (" <> T.take 7 $(gitHash) <> ")"
+    preRelease = if isPreRelease then " (pre-release)" else mempty
 
--- | Version number used in docs
+
+-- | Version number used in docs.
+-- Uses only the two first components of the version. Example: 'v1.1'
 docsVersion :: Text
-docsVersion = "v" <> T.dropEnd 1 (T.dropWhileEnd (/= '.') prettyVersion)
+docsVersion =
+  "v" <> (T.intercalate "." . map show . take 2 $ versionBranch version)
+
+
+-- | Versions with four components (e.g., '1.1.1.1') are treated as pre-releases.
+isPreRelease :: Bool
+isPreRelease =
+  length (versionBranch version) == 4