Prepare v0.27.0 release

- bump version in __init__.py
- add changelog entry (excluding: `#499`, `#503`, Dependabot)

Signed-off-by: Lukas Puehringer <lukas.puehringer@nyu.edu>

CHANGELOG.md

@@ -1,5 +1,31 @@
 # Changelog
 
+## securesystemslib v0.27.0
+
+### Added
+* EXPERIMENTAL DSSE implementation (#487)
+* EXPERIMENTAL sigstore signer and verifier (#522)
+* Minimal TUF/in-toto spec-compliant GPG verifier (#488)
+* API-typical 'import' and 'from URI' GPG signer methods (#488)
+
+### Changed
+* Require public key in GPG signer and disallow subkey signatures (#488)
+* Increase GPG subprocess timeout (#502)
+* Rename default branch to 'main' (#523)
+* Make HSM signer URI configurable (#526)
+* Allow tox to skip virtual HSM tests (#528)
+* Strip PEM keys to compute keyids consistently (#453)
+
+### Removed
+* Internal GPG version utils (#504)
+* Custom subprocess interface (#505)
+* Vendored ssl module (#506)
+
+### Fixed
+* Windows compatibility issues and re-enable Windows CI (#518)
+* GPG subprocess timeout configurability (#502)
+
+
 ## securesystemslib v0.26.0
 
 ### Added

securesystemslib/__init__.py

@@ -1,7 +1,7 @@
 # pylint: disable=missing-module-docstring
 import logging
 
-__version__ = "0.26.0"
+__version__ = "0.27.0"
 
 # Configure a basic 'securesystemslib' top-level logger with a StreamHandler
 # (print to console) and the WARNING log level (print messages of type