Update: dependencies update (OpenTTD#19)

* Update aiohttp from 3.7.4 to 3.7.4.post0
* Update chardet from 3.0.4 to 4.0.0
* Update urllib3 from 1.26.3 to 1.26.4

requirements.txt

@@ -1,8 +1,8 @@
-aiohttp==3.7.4
+aiohttp==3.7.4.post0
 async-timeout==3.0.1
 attrs==20.3.0
 certifi==2020.12.5
-chardet==3.0.4
+chardet==4.0.0
 click==7.1.2
 future==0.18.2
 idna==2.10
@@ -11,5 +11,5 @@ requests==2.25.1
 six==1.15.0
 tinydb==4.4.0
 tuspy==0.2.4
-urllib3==1.26.3
+urllib3==1.26.4
 yarl==1.6.3