Update uncertainties requirement from ~=3.1.1 to ~=3.1.6

[dependabot-preview[bot]]

Updates the requirements on uncertainties to permit the latest version.

Release notes

Sourced from uncertainties's releases.

Global customization of the pretty-print and LaTeX formats

The pretty-print and LaTeX formats can now be customized: the symbols used can be changed (a centered dot can thus for instance be used instead of the usual multiplication symbol).

Unit tests were added for this.

More details are in the Sphinx documentation.

Commits

• 82d857c Updated copyright.
• 1785801 Fixed Sphinx pdflatex compilation. Fixed incorrect index link.
• 365f93f Tests now pass with both Python 2.7 and Python 3.9.
• ea6a7c2 Test for format customization: passes.
• 511f2e4 Consistent names.
• 41573d2 Fixed spurious space in LaTeX representation.
• 44fd4f3 Added release note.
• 3c83b51 Bumped (and fix consistency of) version number.
• a4ffca5 Documented the new pretty-print and LaTeX format customization.
• 9c4f96d Added full customization of the pretty-print and LaTeX formats.
• Additional commits viewable in compare view

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