Update to ez-vcard 0.12.0 (#12)

* Enabled desugaring

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Migrated to Java 8 (failing tests)

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Passed tests

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Reduced `LocalDateTime` to `LocalDate`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Passing unit tests

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Passing instrumentation tests

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Fixed month index

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Fixed month index

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Enabled test from #13

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Removed extra parenthesis

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Minor changes

* Removed wrong "zero-based" comments

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Replaced `toString()` with `DateTimeFormatter`

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Added `KTDoc` and field supported check

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Updated check

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Null-check

Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>

* Update KDoc

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Signed-off-by: Arnau Mora <arnyminer.z@gmail.com>
Co-authored-by: Ricki Hirner <hirner@bitfire.at>