ICU-22561 Added maven-gpg-plugin in pom.xml to sign artifacts for mav… #1157

Job	Run time
clang-valgrind-test	15m 41s
clang-valgrind-intltest (utility)	8m 52s
clang-valgrind-intltest (normalize)	9m 55s
clang-valgrind-intltest (collator)	6m 1s
clang-valgrind-intltest (regex)	7m 1s
clang-valgrind-intltest (format)	29m 22s
clang-valgrind-intltest (translit)	10m 32s
clang-valgrind-intltest (rbbi)	8m 54s
clang-valgrind-intltest (rbnf)	9m 26s
clang-valgrind-intltest (rbnfrt)	7m 37s
clang-valgrind-intltest (icuserv)	6m 3s
clang-valgrind-intltest (idna)	7m 12s
clang-valgrind-intltest (convert)	8m 10s
clang-valgrind-intltest (rbnfp)	6m 5s
clang-valgrind-intltest (csdet)	8m 5s
clang-valgrind-intltest (spoof)	8m 34s
clang-valgrind-intltest (bidi)	6m 16s
	2h 43m 46s

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