Updated spice-vdagent package fixes security vulnerabilities

Matthias Gerstner discovered that SPICE vdagent incorrectly handled the active_xfers hash table. A local attacker could possibly use this issue to cause SPICE vdagent to consume memory, resulting in a denial of service (CVE-2020-25650). Matthias Gerstner discovered that SPICE vdagent incorrectly handled the active_xfers hash table. A local attacker could possibly use this issue to cause SPICE vdagent to consume memory, resulting in a denial of service, or obtain sensitive file contents (CVE-2020-25651). Matthias Gerstner discovered that SPICE vdagent incorrectly handled a large number of client connections. A local attacker could possibly use this issue to cause SPICE vdagent to consume resources, resulting in a denial of service (CVE-2020-25652). Matthias Gerstner discovered that SPICE vdagent incorrectly handled client connections. A local attacker could possibly use this issue to obtain sensitive information, paste clipboard contents, and transfer files into the active session (CVE-2020-25653).