what i missing in my python3 ubuntu 20 env?

[johnfelipe]

root@1-ubuntu-s-8vcpu-16gb-nyc1-01:~/piano_transcription# pip install -r requirements.txt
Collecting h5py==2.10.0
  Using cached h5py-2.10.0-cp38-cp38-manylinux1_x86_64.whl (2.9 MB)
Collecting pandas==1.1.2
  Downloading pandas-1.1.2-cp38-cp38-manylinux1_x86_64.whl (10.4 MB)
     |████████████████████████████████| 10.4 MB 14.8 MB/s
Collecting librosa==0.6.0
  Downloading librosa-0.6.0.tar.gz (1.5 MB)
     |████████████████████████████████| 1.5 MB 69.6 MB/s
Collecting numba==0.48
  Downloading numba-0.48.0-1-cp38-cp38-manylinux2014_x86_64.whl (3.6 MB)
     |████████████████████████████████| 3.6 MB 67.2 MB/s
Collecting mido==1.2.9
  Downloading mido-1.2.9-py2.py3-none-any.whl (52 kB)
     |████████████████████████████████| 52 kB 2.6 MB/s
Collecting mir_eval==0.5
  Downloading mir_eval-0.5.tar.gz (86 kB)
     |████████████████████████████████| 86 kB 11.1 MB/s
Collecting matplotlib==3.0.3
  Downloading matplotlib-3.0.3.tar.gz (36.6 MB)
     |████████████████████████████████| 36.6 MB 36.4 MB/s
    ERROR: Command errored out with exit status 1:
     command: /usr/bin/python3 -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-m3wp3r8i/matplotlib/setup.py'"'"'; __file__='"'"'/tmp/pip-install-m3wp3r8i/matplotlib/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-install-m3wp3r8i/matplotlib/pip-egg-info
         cwd: /tmp/pip-install-m3wp3r8i/matplotlib/
    Complete output (51 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/tmp/pip-install-m3wp3r8i/matplotlib/setup.py", line 225, in <module>
        msg = pkg.install_help_msg()
      File "/tmp/pip-install-m3wp3r8i/matplotlib/setupext.py", line 650, in install_help_msg
        release = platform.linux_distribution()[0].lower()
    AttributeError: module 'platform' has no attribute 'linux_distribution'
    IMPORTANT WARNING:
        pkg-config is not installed.
        matplotlib may not be able to find some of its dependencies
    ============================================================================
    Edit setup.cfg to change the build options

    BUILDING MATPLOTLIB
                matplotlib: yes [3.0.3]
                    python: yes [3.8.5 (default, May 27 2021, 13:30:53)  [GCC
                            9.3.0]]
                  platform: yes [linux]

    REQUIRED DEPENDENCIES AND EXTENSIONS
                     numpy: yes [version 1.18.5]
          install_requires: yes [handled by setuptools]
                    libagg: yes [pkg-config information for 'libagg' could not
                            be found. Using local copy.]
                  freetype: no  [The C/C++ header for freetype2 (ft2build.h)
                            could not be found.  You may need to install the
                            development package.]
                       png: no  [pkg-config information for 'libpng' could not
                            be found.]
                     qhull: yes [pkg-config information for 'libqhull' could not
                            be found. Using local copy.]

    OPTIONAL SUBPACKAGES
               sample_data: yes [installing]
                  toolkits: yes [installing]
                     tests: no  [skipping due to configuration]
            toolkits_tests: no  [skipping due to configuration]

    OPTIONAL BACKEND EXTENSIONS
                       agg: yes [installing]
                     tkagg: yes [installing; run-time loading from Python Tcl /
                            Tk]
                    macosx: no  [Mac OS-X only]
                 windowing: no  [Microsoft Windows only]

    OPTIONAL PACKAGE DATA
                      dlls: no  [skipping due to configuration]

    ============================================================================
                            * The following required packages can not be built:
                            * freetype, png
    ----------------------------------------
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.

[lzh88998]

ensure you are using python 3.7. There are some problems with matplotlib in python 3.8