5.2.0

CHANGES:

• Support MSVC compiler (Jonah Beckford)

• Add extended_errcode_int function (Petter A. Urkedal)

• Fix memory alloc in caml_sqlite3_backup_init()
  (Mark Elvers, Pierre Boutillier, and Benjamin Canou)

• Add Github CI (Yilin Wei)

• Detect pkgconf on Windows/mingw (Mark Elvers, reviewed by Shon Feder)

• Fixed shadowing of agg_ctx when using sizeof.

• Formatted sources using ocamlformat and clang-format.

• Fixed switch syntax error flagged by cppcheck.

• Added .editorconfig.

• Removed superfluous macro conditions.

• Improved API documentation formatting.

• Improved README, license file, copyright notices, and changelog format.