Add release checksums for win32 binary builds.

Verified against archive.mozilla.org and the original builds
on my machine.

releases.sha2

+094b789ee975fbc5ac706b14e5c83f12b92448fa0a55c8a9f7d79afa7f962aae  opusfile-0.1-win32.zip
+33521cef2ef341a938b386439e9879d3e8e916638ffdd5a7d11e09172f307d35  opusfile-0.2-win32.zip
 4248927f2c4e316ea5b84fb02bd100bfec8fa4624a6910d77f0af7f0c6cb8baa  opusfile-0.3.tar.gz
 9836ea11706c44f36de92c4c9b1248e03a4c521e7fb2cff18a0cb4f8b0e79140  opusfile-0.4.tar.gz
 f187906b1b35f7f0d7de6a759b4aab512a9279d23adb35d8009e7e33bd6a922a  opusfile-0.4.zip
+ae23da5963295c6aa13c97becf50ae013e2317706f0e2a9472f2384aa70aaa43  opusfile-0.4-win32.zip
 2ce52d006aeeec9f10260dbe3073c4636954a1ab19c82b8baafefe0180aa4a39  opusfile-0.5.tar.gz
 b940d62beb15b5974764574b9f265481fe5b6ee16902fb705727546caf956261  opusfile-0.5.zip
+93104cab67a2b038753d125028d63c0028a277e798f8ca88df73d4edbfb9a787  opusfile-0.5-win32.zip
 2428717b356e139f18ed2fdb5ad990b5654a238907a0058200b39c46a7d03ea6  opusfile-0.6.tar.gz
 753339225193df605372944889023b9b3c5378d672e8784d69fa241cd465278c  opusfile-0.6.zip
+5c461b6e037f3843b31295c1eefbaf785bf165442f47fc90267bbcbd939b6e1b  opusfile-0.6-win32.zip