Update (src|regtest)/.gitignore - missing sizeshape #3103

Job	Run time
codecheck / codecheck	45m 16s
conda / conda (ubuntu-20.04)	11m 21s
linux / linux (-doc-mpi-)	39m 43s
docker / docker (fedora39)	18m 44s
conda / conda (macos-12)	9m 14s
linux / linux (-mpi-)	53m 50s
mac / macports (macos-12)	15m 16s
docker / docker (rocky8)	22m 55s
conda / conda (macos-14)	2m 7s
linux / linux (-coverage-mpi-)	58m 59s
mac / macports (macos-14)	2m 49s
linux / linux (-debug-)	29m 32s
mac / macports (+allmodules, macos-12)	21m 28s
linux / linux (-debug-mpi-)	38m 30s
mac / macsimple (macos-12)	8m 50s
linux / linux (-intel-)	44m 31s
mac / macsimple (macos-14)	7m 46s
linux / linux (-pycv-mpi-)	19m 55s
	7h 30m 46s

Provide feedback