feat: Bump to singer-sdk v0.43.0 #1120

Job	Run time
Meltano integration test / COPY	58s
Python 3.13 / Postgres 17 / COPY	1m 33s
Meltano integration test / INSERT	58s
Python 3.12 / Postgres 17 / COPY	1m 16s
Python 3.11 / Postgres 17 / COPY	1m 17s
Python 3.10 / Postgres 17 / COPY	1m 10s
Python 3.9 / Postgres 17 / COPY	1m 15s
Python 3.13 / Postgres 13 / COPY	1m 26s
Python 3.13 / Postgres 14 / COPY	1m 23s
Python 3.13 / Postgres 15 / COPY	1m 26s
Python 3.13 / Postgres 16 / COPY	1m 27s
Python 3.13 / Postgres 17 / INSERT	1m 23s
	15m 32s

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