[fix] fix release.sh regex patterns

release.sh

 #!/bin/bash
 
 #__version__     = '0.20.1dev9'
-current=`grep -P "__version__     = \'\d+.\d+.\d+(\w*)\'" duniterpy/__init__.py | grep -oP "\d+.\d+.\d+(\w*)"`
+current=`grep -P "__version__ = \"\d+.\d+.\d+(\w*)\"" duniterpy/__init__.py | grep -oP "\d+.\d+.\d+(\w*)"`
 echo "Current version: $current"
 
 if [[ $1 =~ ^[0-9]+.[0-9]+.[0-9]+[0-9a-z]*$ ]]; then
   # update version in duniterpy
-  sed -i "s/__version__     = '$current'/__version__     = '$1'/g" duniterpy/__init__.py
+  sed -i "s/__version__ = \"$current\"/__version__ = \"$1\"/g" duniterpy/__init__.py
   # update version in documentation configuration
   sed -i "s/version = '$current'/version = '$1'/g" docs/conf.py
   sed -i "s/release = '$current'/release = '$1'/g" docs/conf.py