Release v2.1.0

This minor release puts together the enhancements and fixed accumulated over the
last year. No dramatic changes.

Enhancements:

• pytest: Remove master_key_workflow test case
• pyosdp: cp_init switch to osdp_cp_setup2()
• pytest: Add set/clear flags methods
• libosdp: Add new exported method: osdp_cp_modify_flag()
• libosdp: Add new flag OSDP_PD_FLAG_IGN_UNSOLICITED
• pd: Add check on the length field of osdp_MFGREP
• pytest: remove the need to install python module for tests
• cmake: replace FindPython{Interp,Libs} with FindPython3
• LibOSDP: Consume logger from utils so we don't own that module
• libosdp: Remove -Werror; seems a bit excessive :)
• libosdp: Set an example by not using osdp_cp_setup()
• PD: Prevent out of order CMD_SCRYPT for safety
• libosdp: Mark osdp_cp_setup() as deprecated
• CP: Expose new API osdp_cp_setup2() to discourage use of master_key
• Phy: Nack secure messages received without an active SC session

Fixes:

• Fix an overflow bug in osdp_phy_check_packet()
• Add null checks on struct osdp_file pointer
• pyosdp: Fix handling of temporary flag in LED command
• pytest: Add LED command temporary: False test
• pyosdp: Expose set/clear flags method in the python wrapper
• CP fixup needed when communicating with hardware PD
• Fixed wrong command ID while logging "REPLY_PDID" in OSDP_CP_STATE_IDREQ
• Fix copy-paste issue in cmake/FindMbedTLS.cmake