Bump matplotlib from 3.2.2 to 3.4.0

Bumps [matplotlib](https://github.com/matplotlib/matplotlib) from 3.2.2 to 3.4.0.
- [Release notes](https://github.com/matplotlib/matplotlib/releases)
- [Commits](matplotlib/matplotlib@v3.2.2...v3.4.0)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 cawdrey>=0.3.0
 domdf-python-tools>=1.7.0
 matplotlib>=3.2.2; platform_machine != "aarch64" or python_version > "3.6"
-matplotlib==3.2.2; platform_machine == "aarch64" and python_version == "3.6"
+matplotlib==3.4.0; platform_machine == "aarch64" and python_version == "3.6"
 typing-extensions>=3.7.4.3

tests/requirements.txt

@@ -3,7 +3,7 @@ coverage>=5.1
 coverage-pyver-pragma>=0.2.1
 domdf-python-tools[testing]>=2.0.1
 iniconfig!=1.1.0,>=1.0.1
-matplotlib==3.2.2; platform_machine == "aarch64" and python_version == "3.6"
+matplotlib==3.4.0; platform_machine == "aarch64" and python_version == "3.6"
 pytest>=6.0.0
 pytest-cov>=2.8.1
 pytest-mpl>=0.11