japanese/skkinput3: Mark DEPRECATED

Abandoned, cannot be executed on amd64 due to an error.

$ skkinput3
X Error of failed request: BadValue (integer parameter out of range for operation)

Major opcode of failed request:  18 (X_ChangeProperty)
Value in failed request:  0x40
Serial number of failed request:  39
Current serial number in output stream:  40

PR: 297763
Approved by: koma2@lovepeers.org (maintainer timeout, 2 weeks)
Approved by: osa (mentor)
MFH: 2026Q3

(cherry picked from commit bff649cccba209035ad4d37dc12b29e368c7a284)