Release 4.0.0

[jrothrock]

Cuts the pending changelog entries as 4.0.0 (major) and bumps setup.py 3.5.4 -> 4.0.0

Included:

• Bumped core-agent to 1.6.0 (Bump core-agent to 1.6.0 #860)
• Add core_agent_ca_cert config option to pass --ca-cert to the Core Agent (Add core_agent_ca_cert config option to pass --ca-cert to the Core Agent #855)
• Fix FastMCP tool annotation tags (read_only/idempotent/external/destructive) under FastMCP 4.x (MCP SDK v2), which renamed the ToolAnnotations hint fields from camelCase to snake_case; reads now try snake_case then camelCase, keeping FastMCP 2.x/3.x support (Fix FastMCP tool annotation tags under FastMCP 4.x (MCP SDK v2) #858)
• Bump flake8 pre-commit hook to 7.3.0 for Python 3.12+ compatibility (pyflakes no longer crashes on ast.Str) (Fix FastMCP tool annotation tags under FastMCP 4.x (MCP SDK v2) #858)
• Fix rq instrumentation: use Job.id property instead of removed get_id() (Use Job.id property instead of removed get_id() #851)
• Support FastMCP 3.x while maintaining 2.x backwards compatibility (Support FastMCP 3.x while maintaining 2.x compatibility #852)
• Add security warning for RQ pickle serializer (CWE-502) (Add security warning for RQ pickle serializer (CWE-502) #843)
• Add Redis Cluster instrumentation support (Add Redis Cluster instrumentation support #844)
• Verify Starlette 1.0.0 compatibility (Verify Starlette 1.0.0 compatibility #846)
• Drop Python 3.8/3.9 support, add 3.13/3.14 classifiers (Drop Python 3.8/3.9 support, add 3.13/3.14 classifiers #847)
• Verify 401 responses are not tagged as errors (Verify 401 responses are not tagged as errors (fixes #838) #849)