Update dependency com.thoughtworks.xstream:xstream to v1.4.21

[mend-for-github-com]

This PR contains the following updates:

Package	Type	Update	Change
com.thoughtworks.xstream:xstream (source)	compile	patch	1.4.5 → 1.4.21

By merging this PR, the issue #5 will be automatically resolved and closed:

Severity	CVSS Score	Vulnerability
Critical	9.8	CVE-2013-7285
High	8.5	CVE-2021-39139
High	8.5	CVE-2021-39141
High	8.5	CVE-2021-39144
High	8.5	CVE-2021-39145
High	8.5	CVE-2021-39146
High	8.5	CVE-2021-39147
High	8.5	CVE-2021-39148
High	8.5	CVE-2021-39149
High	8.5	CVE-2021-39150
High	8.5	CVE-2021-39151
High	8.5	CVE-2021-39152
High	8.5	CVE-2021-39153
High	8.5	CVE-2021-39154
High	8.2	CVE-2022-41966
High	8.0	CVE-2020-26217
High	7.5	CVE-2016-3674
High	7.5	CVE-2017-7957
High	7.5	CVE-2021-21341
High	7.5	CVE-2021-29505
High	7.5	CVE-2021-43859
High	7.5	CVE-2024-47072
Medium	6.8	CVE-2020-26259
Medium	6.5	CVE-2021-39140
Medium	6.5	CVE-2022-40151
Medium	6.3	CVE-2020-26258
Medium	6.1	CVE-2021-21346
Medium	6.1	CVE-2021-21347
Medium	6.1	CVE-2021-21349
Medium	5.8	CVE-2021-21345
Medium	5.4	CVE-2021-21351
Medium	5.3	CVE-2021-21342
Medium	5.3	CVE-2021-21343
Medium	5.3	CVE-2021-21344
Medium	5.3	CVE-2021-21348
Medium	5.3	CVE-2021-21350

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