dependabot maven(deps): bump maven-site-plugin from 3.12.1 to 3.20.0

Bumps maven-site-plugin from 3.12.1 to 3.20.0.

Commits

• fd65715 [maven-release-plugin] prepare release maven-site-plugin-3.20.0
• be35f64 [MSITE-945] Remove dependency on Commons IO
• 6fc5d17 [MSITE-945] More modern temporary file handling (#203)
• eb0b0f6 Remove debugging strings from test output (#204)
• 54faaa8 Earlier detection of mkdirs failure (#201)
• 73b57d3 Replace deprecated methods (#198)
• cf5c504 Add version to mrm-maven-plugin
• 688714c Use charset in test (#199)
• adc67e1 Use try with resources to avoid deprecated class (#200)
• 2e867c6 Update history
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