Fix async synchronization and timeouts

[RafaelWO]

Description

After some benchmarking, it seems that setting the semaphore value to the same value as max_connections gives better performance and fewer timeout errors. If wanted, users can change the semaphore value via a keyword argument.

The plot below shows 5 different runs of Unparallel doing 2000 HTTP requests with varying max_connections (x-axis) and semaphore value which is defined by max_connections * semaphore_fact, i.e. for max_connections=300 and semaphore_fact=2 the semaphore value is 600. The y-axis shows the run time in seconds.

The data shows that if the semaphore value is greater than the maximum connections, the run time of finishing the 2000 requests increases drastically.

---

Additionally, some dependencies are upgraded due to CVEs. A policy config for safety is added to ignore a vulnerability in jinja2 that can't be fixed.

Changes

• 🐛 Fix timeouts for cases with lots of requests
• ✏️ Fix typos and code fences in docstrings
• 📝 Display latest alias in docs
• ⬆️ Upgrade anyio from 4.3.0 to 4.4.0 due to CVE
• ⬆️ Upgrade idna from 3.6 to 3.7 due to CVE
• ⬆️ Upgrade requests from 2.31.0 to 2.32.3 due to CVE
• ⬆️ Upgrade tqdm from 4.66.2 to 4.66.4 due to CVE
• 📝 Add synchronization fix to Changelog
• 🔒️ Add safety policy file and ignore jinja2 vulnerability

Related Issue

Relates to #157

Type of Change

• [ ] 📚 Examples / docs / tutorials / dependencies update
• [x] 🔧 Bug fix (non-breaking change which fixes an issue)
• [ ] 🥂 Improvement (non-breaking change which improves an existing feature)
• [ ] 🚀 New feature (non-breaking change which adds functionality)
• [ ] 💥 Breaking change (fix or feature that would cause existing functionality to change)
• [ ] 🔐 Security fix
• [ ] 🔖 Release

Checklist

• [x] I've read the CODE_OF_CONDUCT.md document.
• [x] I've read the CONTRIBUTING.md guide.
• [x] I've updated the code style using make codestyle.
• [x] I've written tests for all new methods and classes that I created.
• [x] I've written the docstring in Google format for all the methods and classes that I used.