Clear unused docker images

Run the following command to clean the unused docker images

docker images -q |xargs docker rmi

Before

bitcoin                   latest              7b35f12891e7        18 minutes ago      167MB
<none>                    <none>              4b24b9dbbd9f        26 minutes ago      167MB
<none>                    <none>              418b6137c28e        35 minutes ago      167MB
debian                    stable-slim         e7e5f8b110eb        10 days ago         69.2MB
mempool/mempool           v1.0                794703676c98        11 days ago         1.01GB
drone/drone               latest              f2e0470417c3        2 months ago        67.5MB
eps                       latest              9c7be9265c84        2 months ago        458MB
<none>                    <none>              54c483efd98e        2 months ago        458MB
<none>                    <none>              306b5cda6db6        2 months ago        458MB
influxdb                  latest              15b283775653        4 months ago        311MB
mlflow                    latest              2390c1d0c9aa        5 months ago        946MB
<none>                    <none>              5f54797bd3bc        5 months ago        946MB
<none>                    <none>              e0d050cd4f39        5 months ago        946MB
<none>                    <none>              cb544a7cbbf4        5 months ago        946MB
<none>                    <none>              81d3d87e6e00        5 months ago        946MB
<none>                    <none>              76deb458df92        5 months ago        946MB
<none>                    <none>              ff5c93f1c05e        5 months ago        430MB
<none>                    <none>              3ccee6bb3930        5 months ago        638MB
<none>                    <none>              49104572fcb2        5 months ago        638MB
<none>                    <none>              18875f41afe1        5 months ago        1.22GB
<none>                    <none>              93c114c8870f        5 months ago        1.22GB
<none>                    <none>              8e2959da3ce1        5 months ago        1.22GB
<none>                    <none>              a392e8be4b98        5 months ago        1.22GB
<none>                    <none>              11241beda07a        5 months ago        1.22GB
<none>                    <none>              23e94992e3e4        5 months ago        1.2GB
<none>                    <none>              e22cc69bbfde        5 months ago        1.2GB
<none>                    <none>              5d3b30cf7774        5 months ago        1.2GB
<none>                    <none>              d055ea146c1e        5 months ago        1.2GB
<none>                    <none>              8163fda4e56b        5 months ago        1.2GB
<none>                    <none>              b990dc02b0dc        5 months ago        1.2GB
<none>                    <none>              7f3f8a79a336        5 months ago        1.2GB
<none>                    <none>              4bc4af0d6774        5 months ago        1.2GB
redis                     latest              de25a81a5a0b        5 months ago        98.2MB
gitea/gitea               latest              9f07e22ee4b9        7 months ago        109MB
ruimarinho/bitcoin-core   <none>              9a73f94058c2        7 months ago        168MB
python                    3.7.0               a187104266fb        18 months ago       922MB

After

REPOSITORY          TAG                 IMAGE ID            CREATED             SIZE
bitcoin             latest              7b35f12891e7        30 minutes ago      167MB
debian              stable-slim         e7e5f8b110eb        10 days ago         69.2MB
mempool/mempool     v1.0                794703676c98        11 days ago         1.01GB
eps                 latest              9c7be9265c84        2 months ago        458MB
influxdb            latest              15b283775653        4 months ago        311MB
mlflow              latest              2390c1d0c9aa        5 months ago        946MB
gitea/gitea         latest              9f07e22ee4b9        7 months ago        109MB