v0.3.8

• Minor changes:
  • Stable URL-encoding for Forms (see #67):
    • Introduce urlEncodeParams and urlDecodeParams;
    • Introduce urlEncodeAsFormStable and use stable encoding for doctests;
    • Add toEntriesByKeyStable and toListStable;
  • Add Semigroup instance for Form (see #69);
  • Relax upper bound on Cabal (see #73).