CERTIFICATE_VERIFY_FAILED on docker container

[ahmet]

I want to try Speedtest-cli on docker container and I get a SSL error
```root@test-sv:/# speedtest-cli
Retrieving speedtest.net configuration...
Cannot retrieve speedtest configuration
ERROR: <urlopen error [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:852)>
```
I think it might be caused by non installed depency and I checked depencies on ubuntu, ca-certificates does not appear.

```bash
root@test-sv:/# apt install speedtest-cli
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
  file libexpat1 libmagic-mgc libmagic1 libmpdec2 libpython-stdlib libpython2.7-minimal libpython2.7-stdlib libpython3-stdlib libpython3.6-minimal
  libpython3.6-stdlib libreadline7 libsqlite3-0 libssl1.1 mime-support python python-minimal python-pkg-resources python2.7 python2.7-minimal python3
  python3-minimal python3-pkg-resources python3.6 python3.6-minimal readline-common xz-utils
Suggested packages:
  python-doc python-tk python-setuptools python2.7-doc binutils binfmt-support python3-doc python3-tk python3-venv python3-setuptools python3.6-venv
  python3.6-doc readline-doc
The following NEW packages will be installed:
  file libexpat1 libmagic-mgc libmagic1 libmpdec2 libpython-stdlib libpython2.7-minimal libpython2.7-stdlib libpython3-stdlib libpython3.6-minimal
  libpython3.6-stdlib libreadline7 libsqlite3-0 libssl1.1 mime-support python python-minimal python-pkg-resources python2.7 python2.7-minimal python3
  python3-minimal python3-pkg-resources python3.6 python3.6-minimal readline-common speedtest-cli xz-utils
0 upgraded, 28 newly installed, 0 to remove and 21 not upgraded.
Need to get 10.9 MB of archives.
After this operation, 52.1 MB of additional disk space will be used.
Do you want to continue? [Y/n]
```
After installing ca-certificate i don't get any error.
I think required packages needs a small update and ca-certifaces include a required package.