Public Sans v1.006

• Adds a new python-based build script for generating webfonts and variable fonts. Use /.build.sh from the project directory. Based on https://github.com/thundernixon/googlefonts-qa-template/blob/master/sources/build.sh
• Moves to 2000 UPM
• Adjusts kerning overall
• Improves vertical metrics
• Rounds counters in b, d, p, and q glyphs
• Widens o and e glyphs
• Narrows s glyph
• Slightly squares curves in rounded lowercase thin glyphs
• Squares counters on S and C glyphs
• Aligns C and G glyph upper terminals
• Improves output of variable fonts
• Outputs better binaries for Font Bakery (https://github.com/googlefonts/fontbakery)