Straightforward maintenance update for cad/opencascade to version 7.8.1.
Both its consumers cad/{kicad,prusaslicer} build and run fine.

Index: Makefile
===================================================================
RCS file: /cvs/ports/cad/opencascade/Makefile,v
retrieving revision 1.3
diff -u -p -r1.3 Makefile
--- Makefile	10 Feb 2024 15:39:40 -0000	1.3
+++ Makefile	18 Apr 2024 12:26:45 -0000
@@ -1,7 +1,7 @@
 COMMENT =		platform for 3D CAD, CAM, and CAE
 DPB_PROPERTIES =	parallel
 
-V =			7.8.0
+V =			7.8.1
 DISTNAME =		opencascade-${V}
 
 .for LIB in TKBO TKBRep TKBin TKBinL TKBinTObj TKBinXCAF TKBool TKCAF TKCDF \
Index: distinfo
===================================================================
RCS file: /cvs/ports/cad/opencascade/distinfo,v
retrieving revision 1.2
diff -u -p -r1.2 distinfo
--- distinfo	10 Feb 2024 15:39:40 -0000	1.2
+++ distinfo	18 Apr 2024 12:26:45 -0000
@@ -1,2 +1,2 @@
-SHA256 (opencascade-7.8.0.tar.gz) = ucjwqdUjrBpgZpf5X8Odis8RQNNyhWG4AQpgRDG06c8=
-SIZE (opencascade-7.8.0.tar.gz) = 48431454
+SHA256 (opencascade-7.8.1.tar.gz) = M/K9tn4/auRp8/qBbPujRSmiOpy3Nr+YoysgPYUxxSM=
+SIZE (opencascade-7.8.1.tar.gz) = 48427425
Index: pkg/PLIST
===================================================================
RCS file: /cvs/ports/cad/opencascade/pkg/PLIST,v
retrieving revision 1.3
diff -u -p -r1.3 PLIST
--- pkg/PLIST	10 Feb 2024 15:39:40 -0000	1.3
+++ pkg/PLIST	18 Apr 2024 12:26:45 -0000
@@ -1,9 +1,9 @@
 @conflict oce-*
 @pkgpath cad/oce
 bin/DRAWEXE
-@bin bin/DRAWEXE-7.8.0
+@bin bin/DRAWEXE-7.8.1
 bin/ExpToCasExe
-@bin bin/ExpToCasExe-7.8.0
+@bin bin/ExpToCasExe-7.8.1
 bin/occt_custom.sh
 bin/occt_custom_${COMP}_${BITS}.sh
 bin/occt_draw.sh