Close statements after use

[apkhandkar]

Not doing so was leading to a "maximum open cursors exceeded" error.

[dmjio]

Nice, maybe it's worth making a withStatement function that automatically performs closeStatement (like withHandle). I can update the nix hash in a separate PR.

withStmt conn sql action = do
  stmt <- prepareStmt conn sql
  result <- action stmt
  closeStatement stmt
  pure result

[dmjio]

@apkhandkar sorry, I should not have merged this, I assumed this was something you were upstreaming that was a fix.

• stmt is not in scope so there is a compile error (fixed in closeStatement #55)
• closeStatement is causing test failures

If I get bandwidth I'll come back to the test failures, or if you'd like to upstream the fix.