Use ubuntu-20.04 image for all Linux CI runs

.github/workflows/publish-android.yaml

@@ -10,7 +10,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - name: "Install Android NDK 21.4.7075529"
         run: |

.github/workflows/publish-jvm.yaml

@@ -46,7 +46,7 @@ jobs:
   build-jvm-full-library:
     name: Create full bdk-jvm library
     needs: [build-jvm-macOS-M1-native-lib]
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - name: Checkout publishing branch
         uses: actions/checkout@v2

.github/workflows/publish-python.yaml

@@ -9,7 +9,7 @@ on: [workflow_dispatch]
 jobs:
   build-manylinux2014-x86_64-wheel:
     name: "Build Manylinux 2014 x86_64 wheel"
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     defaults:
       run:
         working-directory: bdk-python
@@ -131,7 +131,7 @@ jobs:
 
   publish-pypi:
     name: "Publish on PyPI"
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     defaults:
       run:
         working-directory: bdk-python

.github/workflows/test-android.yaml

@@ -19,7 +19,7 @@ env:
 
 jobs:
   build:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     steps:
       - name: "Install Android NDK 21.4.7075529"
         run: |

.github/workflows/test-python.yaml

@@ -18,7 +18,7 @@ on:
 jobs:
   build-manylinux2014-x86_64-wheel:
     name: "Build and test Manylinux 2014 x86_64 wheels"
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-20.04
     defaults:
       run:
         working-directory: bdk-python