chore(docs/decisions-log.md): document mysql-connector-java downgrade

[skip ci]

Author: php-coder

docs/decisions-log.md

@@ -15,6 +15,7 @@
 | 09.02.2020 Workaround | **pdd** fails to parse files in charsets other than UTF-8 with error `invalid byte sequence in UTF-8`. Workaround: exclude `src/test/wiremock` directory. Bug: [yegor256/pdd#143](https://github.com/yegor256/pdd/issues/143) Commits: [30aab7d](https://github.com/php-coder/mystamps/commit/30aab7dc8c265804efef382422e7cae9e53187f3), [ab563b6](https://github.com/php-coder/mystamps/commit/ab563b653279625120121babccdfd915181ee46d) |
 | 07.02.2020 Workaround | [php-coder/mystamps#1248](https://github.com/php-coder/mystamps/issues/1248): **wiremock** logs warnings for static resources when there is no stub mapping. Workaround: create mappings for such resources. Bug: [tomakehurst/wiremock#1247](https://github.com/tomakehurst/wiremock/issues/1247) Commits: [0018ad4](https://github.com/php-coder/mystamps/commit/0018ad44a21379b8179f94e954795c66b6d50bbc) |
 | ~~24.11.2019 Workaround~~ | ~~[php-coder/mystamps#1156](https://github.com/php-coder/mystamps/issues/1156) After updating **html5validator** to 0.3.2, the `--ignore-re` has stopped to work. Workaround: revert and pin the version to 0.3.1 Bug: [svenkreiss/html5validator#64](https://github.com/svenkreiss/html5validator/issues/64) Commits: [9a0d695](https://github.com/php-coder/mystamps/commit/9a0d695ccac1deeba0c4280779bbac11ebf3ac4d)~~<br/> UPDATE(22.12.2020): in [61c97a4f](https://github.com/php-coder/mystamps/commit/61c97a4f2435e7cdf17c0ad6866f7b99cb640e3b) ([#1169](https://github.com/php-coder/mystamps/issues/1169)) html5validator has been updated to 0.3.3 that fixed the issue |
+| 29.09.2018 Workaround | After [upgrade of **mysql-connector-java** to 5.1.47](https://github.com/php-coder/mystamps/commit/21e3a7a361990d6059cb7668c1217f653bd0ae8f), the bug that [causes NullPointerException](https://travis-ci.org/php-coder/mystamps/jobs/435000067) was revealed. I reverted the version back to 5.1.46 Issue: https://bugs.mysql.com/bug.php?id=92089 Commits: [3cb0dac9](https://github.com/php-coder/mystamps/commit/3cb0dac9fb62bbc12331b7ea1378f3b56746714d) |
 | 30.12.2017 Workaround | [php-coder/mystamps#772](https://github.com/php-coder/mystamps/issues/772) Because **Travis CI** has **MySQL** version 5.6.43, we can't have a unique index on a column that has a length that exceeds 767 bytes. Our production server is running on 5.7.20 that doesn't have such limitation. In order to be able to run migrations on all the environments, I set type of the `series_import_requests.url` column to `VARCHAR(767)` (instead of `VARCHAR(768)` or `VARCHAR(1024)` as I wanted before). Commits: [33dd9025](https://github.com/php-coder/mystamps/commit/33dd902500501d3fdc3a744229ad921982adbc01) |
 | 28.09.2016 Workaround | Because **Travis CI** has **MySQL** version 5.5.53 (that is less than 5.6.5 but the latest for Ubuntu 12.04), we couldn't create a column with `NOW()` as a default value. We did the same in 3 steps to support this old version. Commits: [d55cd6cc](https://github.com/php-coder/mystamps/commit/d55cd6cc0842bc938c5c30f9aaaf78697ba84f45), [566d72f0](https://github.com/php-coder/mystamps/commit/566d72f053d785afb58234a6c7d69510a35bb7c4) |
 | 30.01.2016 Workaround | **html5validator** complained about `An "img" element must have an "alt" attribute`. I've suppressed this error until [php-coder/mystamps#314](https://github.com/php-coder/mystamps/issues/314) is fixed. Commits: [ec40a6ad](https://github.com/php-coder/mystamps/commit/ec40a6ad431b77c922195bd3225a4963416cea43) |