test: Remove i686 from test/get_previous_releases.py

It is not possible to run the compatibility tests on i686 because the
releases v20+ are missing for that arch. It would be possible to
self-compile those releases, but then one can also self-compile
0.15-0.19.

test/get_previous_releases.py

@@ -23,32 +23,27 @@ import hashlib
 SHA256_SUMS = {
     "d40f18b4e43c6e6370ef7db9131f584fbb137276ec2e3dba67a4b267f81cb644": "bitcoin-0.15.2-aarch64-linux-gnu.tar.gz",
     "54fb877a148a6ad189a1e1ab1ff8b11181e58ff2aaf430da55b3fd46ae549a6b": "bitcoin-0.15.2-arm-linux-gnueabihf.tar.gz",
-    "2b843506c3f1af0eeca5854a920264f9a829f02d0d50328005950ddcbe88874d": "bitcoin-0.15.2-i686-pc-linux-gnu.tar.gz",
     "87e9340ff3d382d543b2b69112376077f0c8b4f7450d372e83b68f5a1e22b2df": "bitcoin-0.15.2-osx64.tar.gz",
     "566be44190fd76daa01f13d428939dadfb8e3daacefc8fa17f433cad28f73bd5": "bitcoin-0.15.2-x86_64-linux-gnu.tar.gz",
     #
     "0768c6c15caffbaca6524824c9563b42c24f70633c681c2744649158aa3fd484": "bitcoin-0.16.3-aarch64-linux-gnu.tar.gz",
     "fb2818069854a6ad20ea03b28b55dbd35d8b1f7d453e90b83eace5d0098a2a87": "bitcoin-0.16.3-arm-linux-gnueabihf.tar.gz",
-    "75a537844313b0a84bdb61ffcdc5c4ce19a738f7ddf71007cd2edf664efd7c37": "bitcoin-0.16.3-i686-pc-linux-gnu.tar.gz",
     "78c3bff3b619a19aed575961ea43cc9e142959218835cf51aede7f0b764fc25d": "bitcoin-0.16.3-osx64.tar.gz",
     "5d422a9d544742bc0df12427383f9c2517433ce7b58cf672b9a9b17c2ef51e4f": "bitcoin-0.16.3-x86_64-linux-gnu.tar.gz",
     #
     "5a6b35d1a348a402f2d2d6ab5aed653a1a1f13bc63aaaf51605e3501b0733b7a": "bitcoin-0.17.2-aarch64-linux-gnu.tar.gz",
     "d1913a5d19c8e8da4a67d1bd5205d03c8614dfd2e02bba2fe3087476643a729e": "bitcoin-0.17.2-arm-linux-gnueabihf.tar.gz",
-    "d295fc93f39bbf0fd937b730a93184899a2eb6c3a6d53f3d857cbe77ef89b98c": "bitcoin-0.17.2-i686-pc-linux-gnu.tar.gz",
     "a783ba20706dbfd5b47fbedf42165fce70fbbc7d78003305d964f6b3da14887f": "bitcoin-0.17.2-osx64.tar.gz",
     "943f9362b9f11130177839116f48f809d83478b4c28591d486ee9a7e35179da6": "bitcoin-0.17.2-x86_64-linux-gnu.tar.gz",
     #
     "88f343af72803b851c7da13874cc5525026b0b55e63e1b5e1298390c4688adc6": "bitcoin-0.18.1-aarch64-linux-gnu.tar.gz",
     "cc7d483e4b20c5dabd4dcaf304965214cf4934bcc029ca99cbc9af00d3771a1f": "bitcoin-0.18.1-arm-linux-gnueabihf.tar.gz",
-    "989e847b3e95fc9fedc0b109cae1b4fa43348f2f712e187a118461876af9bd16": "bitcoin-0.18.1-i686-pc-linux-gnu.tar.gz",
     "b7bbcee7a7540f711b171d6981f939ca8482005fde22689bc016596d80548bb1": "bitcoin-0.18.1-osx64.tar.gz",
     "425ee5ec631ae8da71ebc1c3f5c0269c627cf459379b9b030f047107a28e3ef8": "bitcoin-0.18.1-riscv64-linux-gnu.tar.gz",
     "600d1db5e751fa85903e935a01a74f5cc57e1e7473c15fd3e17ed21e202cfe5a": "bitcoin-0.18.1-x86_64-linux-gnu.tar.gz",
     #
     "3a80431717842672df682bdb619e66523b59541483297772a7969413be3502ff": "bitcoin-0.19.1-aarch64-linux-gnu.tar.gz",
     "657f28213823d240dd3324d14829702f9ad6f0710f8bdd1c379cb3c447197f48": "bitcoin-0.19.1-arm-linux-gnueabihf.tar.gz",
-    "10d1e53208aa7603022f4acc084a046299ab4ccf25fe01e81b3fb6f856772589": "bitcoin-0.19.1-i686-pc-linux-gnu.tar.gz",
     "1ae1b87de26487075cd2fd22e0d4ead87d969bd55c44f2f1d873ecdc6147ebb3": "bitcoin-0.19.1-osx64.tar.gz",
     "aa7a9563b48aa79252c8e7b6a41c07a5441bd9f14c5e4562cc72720ea6cb0ee5": "bitcoin-0.19.1-riscv64-linux-gnu.tar.gz",
     "5fcac9416e486d4960e1a946145566350ca670f9aaba99de6542080851122e4c": "bitcoin-0.19.1-x86_64-linux-gnu.tar.gz",