build: replace winrar dependency by 7z (#1077)

README.md

@@ -188,7 +188,7 @@ Building Sourcetrail requires several dependencies to be in place on your machin
 
 ### Required Tools
 
-* __WinRAR (required for Windows)__
+* __7z (required for Windows)__
     * __REASON__: Used to extract the prebuilt SourcetrailPythonIndexer which is downloaded automatically during build execution.
 
 ### Building

appveyor.yml

@@ -12,8 +12,6 @@ install:
   - ninja --version
 
 before_build:
-    - choco install winrar -y
-    - SET "PATH=%PATH%;C:\Program Files\WinRAR"
     - mkdir build
     - cd build
     - mkdir temp

script/download_python_indexer.sh

@@ -87,7 +87,7 @@ if [ $PLATFORM == "linux" ]; then
 elif [ $PLATFORM == "osx" ]; then
 	unzip -d $TEMP_PATH $TEMP_PATH/$PACKAGE_FILE_NAME
 elif [ $PLATFORM == "windows" ]; then
-	winrar x $TEMP_PATH/$PACKAGE_FILE_NAME $TEMP_PATH
+    7z x $TEMP_PATH/$PACKAGE_FILE_NAME -o$TEMP_PATH
 fi