diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 3c222d9..353cfd4 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -6,10 +6,10 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     strategy:
         matrix:
-          python-version: ['3.6.x', '3.7.x', '3.8.x']
+          python-version: ['3.7.x', '3.8.x']
     steps:
       - name: Checkout
         uses: actions/checkout@v1
diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 9ddd13b..49d389f 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -8,10 +8,10 @@ on:
 
 jobs:
   test-unit:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     strategy:
         matrix:
-          python-version: ['3.6.x', '3.7.x', '3.8.x']
+          python-version: ['3.7.x', '3.8.x']
     steps:
       - name: Checkout
         uses: actions/checkout@v1
diff --git a/.github/workflows/pypi_publish.yml b/.github/workflows/pypi_publish.yml
index 7ca8f7d..f54149e 100644
--- a/.github/workflows/pypi_publish.yml
+++ b/.github/workflows/pypi_publish.yml
@@ -6,7 +6,7 @@ on:
 
 jobs:
   release:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/setup-python@v2
         with:
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index bc1dfee..6864198 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -5,7 +5,7 @@ on: [workflow_dispatch]
 jobs:
   release:
     name: Create Release
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/setup-python@v2
         with:
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 15f173d..6c29ebf 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -3,3 +3,4 @@ isort
 mypy
 pytest
 pytest-cov
+types-requests
\ No newline at end of file
diff --git a/snooker/api/snooker_org.py b/snooker/api/snooker_org.py
index 74a5e74..a8d7d93 100644
--- a/snooker/api/snooker_org.py
+++ b/snooker/api/snooker_org.py
@@ -1,4 +1,6 @@
-from typing import List, Optional, Type, Literal  # noqa
+from typing import List, Optional
+
+from typing_extensions import Literal
 
 from snooker.api.base import BaseApi
 from snooker.models.snooker_org.event import Event
@@ -8,6 +10,8 @@
 from snooker.models.snooker_org.round import Round
 from snooker.models.snooker_org.seeding import Seeding
 
+PlayerStatus = Literal['a', 'p']
+
 
 class SnookerOrgApi(BaseApi):
     """
@@ -121,7 +125,7 @@ def event_players(self, event_id: int) -> Optional[List[Player]]:
 
         return self._get_two_dimensional(params, model)
 
-    def players(self, status: Literal['a', 'p'], season: Optional[int]) -> Optional[List[Player]]:
+    def players(self, status: PlayerStatus, season: Optional[int]) -> Optional[List[Player]]:
         """
         Retrieve list of all players in the tour in given season.
 
@@ -212,7 +216,7 @@ def head_to_head(self, player_1_id: int, player_2_id: int, season: Optional[int]
 
         :param player_1_id: ID of a first player
         :param player_2_id: ID of a second player
-        :param season: Season for which data is collected. Use -1 for all seasons (current season if no season provided).
+        :param season: Season for which data is collected. Use -1 for all seasons (current if no season provided).
         :return: List of matches (if available)
         """
         params = {'p1': player_1_id, 'p2': player_2_id, 's': season}