chore(luassert): bump to v1.9.0

[stasjok]

I wanted to update languages/en.lua in order to properly fix #376, because last time language file was not updated in #377, but it's required. After this change it looks like this:

Fail    ||      plugin/format configure_format sets up format on save for matching client
            tests/nvim/unit/plugin/format_spec.lua:98: Function was never called with matching arguments.
            Called with (last call if any):
            (values list) ((string) 'BufWritePre', (table: 0x7f3b2e6bb060) {
              [buffer] = 1
              [callback] = function: 0x7f3b2e6b8798
              [desc] = 'Format on save'
              [group] = 3 })
            Expected:
            (values list) ((string) 'BufWritePre', (table: 0x7f3b2e6c5180) {
              [buffer] = 1
              [callback] = function: 0x7f3b2e6c5230
              [desc] = 'Format on save'
              [group] = 3 })
            
            stack traceback:
                tests/nvim/unit/plugin/format_spec.lua:98: in function 'assert_configure_format'
                tests/nvim/unit/plugin/format_spec.lua:237: in function <tests/nvim/unit/plugin/format_spec.lua:231>

While I'm at it I also updated luassert to latest version.