Update mysql version on libmysqclient job

Apparently these files don't stay available forever. Update to
a newer version.

Author: nikic

azure/libmysqlclient_job.yml

@@ -32,6 +32,6 @@ jobs:
         libmysql: mysql-5.7.31-linux-glibc2.12-x86_64.tar.gz
     - template: libmysqlclient_test.yml
       parameters:
-        configurationName: ${{ parameters.configurationName }} - MySQL 8.0.21
-        libmysql: mysql-8.0.21-linux-glibc2.12-x86_64.tar.xz
+        configurationName: ${{ parameters.configurationName }} - MySQL 8.0.24
+        libmysql: mysql-8.0.24-linux-glibc2.12-x86_64.tar.xz
         configurationParameters: ${{ parameters.configurationParameters }} --enable-werror