Upgrade to at least ISCE2 v2.6.3 and Python 3.10

[jtherrmann]

Jira: https://asfdaac.atlassian.net/browse/TOOL-3399

Note: The above link is accessible only to members of ASF.

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We should upgrade to the latest versions of ISCE2 and Python that will work with this plugin. We're currently pinned to python>=3.9,<3.10 and isce2=2.6.1.dev7 in environment.yml. The Python pin is due to isce-framework/isce2#458, which recommends upgrading to ISCE2 v2.6.3 for Python 3.10 support. Per @jhkennedy via this Mattermost thread, there's currently some tight coupling between autoRIFT and ISCE2 which makes it difficult for us to upgrade ISCE2, so this issue is blocked until that coupling is removed.