Bump matplotlib from 3.3.3 to 3.3.4

Bumps matplotlib from 3.3.3 to 3.3.4.

Release notes

Sourced from matplotlib's releases.

REL: v3.3.4

This is the fourth bugfix release of the 3.3.x series.

This release contains several critical bug-fixes:

• Fix WebAgg initialization.
• Fix parsing QT_API setting with mixed case.
• Fix build with link-time optimization disabled in environment.
• Fix test compatibility with NumPy 1.20.
• Fix test compatibility with pytest 6.2.

Commits

• 396e8c7 REL: v3.3.4
• 188a6fb Merge branch 'v3.3.3-doc' into v3.3.x
• 6adafce DOC: Update GitHub stats for 3.3.3.
• bae33a0 Merge pull request #19386 from meeseeksmachine/auto-backport-of-pr-19238-on-v...
• 81305b4 Backport PR #19238: Fix build with LTO disabled in environment
• db5b330 Merge pull request #19382 from meeseeksmachine/auto-backport-of-pr-19052-on-v...
• 491c957 Backport PR #19052: Always pass integers to wx.Size.
• d262e53 Merge pull request #19377 from meeseeksmachine/auto-backport-of-pr-19371-on-v...
• 6381656 Backport PR #19371: Fix specgram test on NumPy 1.20.
• a9ff466 Merge pull request #19305 from QuLogic/auto-backport-of-pr-19301-on-v3.3.x
• Additional commits viewable in compare view