[GHA] Get rid of Ubuntu 20 runners (#28938)

Support of Ubuntu 20.04 ends in April

Signed-off-by: Alina Kladieva <alina.kladieva@intel.com>

Author: akladiev

.github/workflows/build_doc.yml

@@ -14,7 +14,7 @@ permissions: read-all
 
 jobs:
   Build_Doc:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: ${{ github.repository_owner == 'openvinotoolkit' }}
     steps:
       - name: Clone OpenVINO

.github/workflows/py_checks.yml

@@ -24,7 +24,7 @@ permissions: read-all
 
 jobs:
   linters:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-22.04
     if: ${{ github.repository_owner == 'openvinotoolkit' }}
     steps:
       - name: Clone OpenVINO