While revisiting an old Python project you may come to realize that your requirements.txt file contains out of date versions. You could go through and research each library and get it's latest version number but may be discouraged if there too many.
The following is a technique to update the entire file without having to take too much time.
This technique is good if your goal to to update each library to it's most recent first.
This will unpin the reference to a specific version
amqp==1.4.9
anyjson==0.3.3
BeautifulSoup==3.2.1
billiard==3.3.0.23
celery==3.1.13
certifi==2018.1.18
chardet==3.0.4
Django==1.6.6
django-extensions==1.3.11
django-celery==3.1.1
idna==2.6
kombu==3.0.37
pytz==2018.3
requests==2.18.4
six==1.7.3
urllib3==1.22
vine==1.1.4
amqp>=1.4.9
anyjson>=0.3.3
BeautifulSoup>=3.2.1
billiard>=3.3.0.23
celery>=3.1.13
certifi>=2018.1.18
chardet>=3.0.4
Django>=1.6.6
django-extensions>=1.3.11
django-celery>=3.1.1
idna>=2.6
kombu>=3.0.37
pytz>=2018.3
requests>=2.18.4
six>=1.7.3
urllib3>=1.22
vine>=1.1.4
$ pip install -r requirements.txt --upgrade
$ pip list
$ pip freeze > requirements.txt