[Security] Bump pyyaml from 3.10 to 5.3.1 in /requirements

[dependabot-preview]

Bumps pyyaml from 3.10 to 5.3.1. This update includes security fixes.

Vulnerabilities fixed

Sourced from The GitHub Security Advisory Database.

Improper Input Validation in PyYAML A vulnerability was discovered in the PyYAML library in versions before 5.3.1, where it is susceptible to arbitrary code execution when it processes untrusted YAML files through the full_load method or with the FullLoader loader. Applications that use the library to process untrusted input may be vulnerable to this flaw. An attacker could use this flaw to execute arbitrary code on the system by abusing the python/object/new constructor.

Affected versions: < 5.3.1

Sourced from The GitHub Security Advisory Database.

High severity vulnerability that affects pyyaml In PyYAML before 4.1, the yaml.load() API could execute arbitrary code. In other words, yaml.safe_load is not used.

Affected versions: < 4.2b1

Changelog

Sourced from pyyaml's changelog.

5.3.1 (2020-03-18)

• yaml/pyyaml#386 -- Prevents arbitrary code execution during python/object/new constructor

5.3 (2020-01-06)

• yaml/pyyaml#290 -- Use is instead of equality for comparing with None
• yaml/pyyaml#270 -- Fix typos and stylistic nit
• yaml/pyyaml#309 -- Fix up small typo
• yaml/pyyaml#161 -- Fix handling of slots
• yaml/pyyaml#358 -- Allow calling add_multi_constructor with None
• yaml/pyyaml#285 -- Add use of safe_load() function in README
• yaml/pyyaml#351 -- Fix reader for Unicode code points over 0xFFFF
• yaml/pyyaml#360 -- Enable certain unicode tests when maxunicode not > 0xffff
• yaml/pyyaml#359 -- Use full_load in yaml-highlight example
• yaml/pyyaml#244 -- Document that PyYAML is implemented with Cython
• yaml/pyyaml#329 -- Fix for Python 3.10
• yaml/pyyaml#310 -- Increase size of index, line, and column fields
• yaml/pyyaml#260 -- Remove some unused imports
• yaml/pyyaml#163 -- Create timezone-aware datetimes when parsed as such
• yaml/pyyaml#363 -- Add tests for timezone

5.2 (2019-12-02)

• Repair incompatibilities introduced with 5.1. The default Loader was changed, but several methods like add_constructor still used the old default yaml/pyyaml#279 -- A more flexible fix for custom tag constructors yaml/pyyaml#287 -- Change default loader for yaml.add_constructor yaml/pyyaml#305 -- Change default loader for add_implicit_resolver, add_path_resolver
• Make FullLoader safer by removing python/object/apply from the default FullLoader yaml/pyyaml#347 -- Move constructor for object/apply to UnsafeConstructor
• Fix bug introduced in 5.1 where quoting went wrong on systems with sys.maxunicode <= 0xffff yaml/pyyaml#276 -- Fix logic for quoting special characters
• Other PRs: yaml/pyyaml#280 -- Update CHANGES for 5.1

5.1.2 (2019-07-30)

• Re-release of 5.1 with regenerated Cython sources to build properly for Python 3.8b2+

5.1.1 (2019-06-05)

• Re-release of 5.1 with regenerated Cython sources to build properly for Python 3.8b1

5.1 (2019-03-13)

... (truncated)

Commits

• 538b5c9 Update announcement.msg
• 8a01c99 Move test files back into tests/data/
• 91bca4b Update version to 5.3.1
• 5080ba5 Prevents arbitrary code execution during python/object/new constructor (#386)
• 2f463cf Update announcement.msg
• 377092f Changes for 5.3
• 69b025a Changes for 5.3b1
• 4fcdcdb Add tests for timezone (#363)
• 96d65f3 Create timezone-aware datetimes when parsed as such (#163)
• 49b3548 tox.ini: passenv = PYYAML_TEST_GROUP
• Additional commits viewable in compare view

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