(#51) Linux: improve tests on CI

Author: ForNeVeR

.github/workflows/main.yml

@@ -21,11 +21,8 @@ jobs:
 
       - name: Checkout
         uses: actions/checkout@v2
-      - run: cd $GITHUB_WORKSPACE
-      - run: ls
-      - run: pwd
-      - name: Initialize repository submodules
-        run: git submodule init
+        with:
+          submodules: true
 
       # Build:
       - name: Install
@@ -76,9 +73,8 @@ jobs:
       NUGET_PACKAGES: ${{ github.workspace }}/.github/nuget-packages
       PACKAGE_VERSION_BASE: 1.7.9
     steps:
-      - run: apt-get update
       - name: Set up Git
-        run: apt-get install git
+        run: apt-get update && apt-get install -y software-properties-common && apt-get update && add-apt-repository -y ppa:git-core/ppa && apt-get update && apt-get install -y git
 
       - name: Checkout
         uses: actions/checkout@v2

MAINTAINERSHIP.md

@@ -8,7 +8,7 @@ Publish a New Version
 2. Update the license, if required.
 3. Update the copyright year in the `copyright` section of the `tdlib.native.nuspec` file.
 4. Update the version in the following places:
-    - `.github/workflows/main.yml`: `PACKAGE_VERSION_BASE` environment variable
+    - `.github/workflows/main.yml`: `PACKAGE_VERSION_BASE` environment variable (2 occurrences)
     - `common/download-release.ps1`: `$Version` variable default value
     - `common/nuget-pack.ps1`: `$Version` variable default value
     - `.appveyor.yml`: `test_script` section (2 occurrences)