Makefile Error when building pg_duckdb locally

### What happens?

Machine is running rhel9 and I'm trying to build the pg_duckdb extension locally from source but get an error during the make command:

```
/usr/bin/install -c -m 644 .//pg_duckdb.control '/home/username/projects/postgresql17-pg_duckdb/BUILDROOT/postgresql17-pg_d
uckdb-0.0.1-4.g35026b3.el9.x86_64/usr/pgsql-17/share/extension/'
Putting child 0x563c6f6cfc50 (install) PID 1987557 on the chain.
Live child 0x563c6f6cfc50 (install) PID 1987557
Reaping winning child 0x563c6f6cfc50 PID 1987557
/usr/bin/install -c -m 644 .//pg_duckdb.control .//sql/pg_duckdb--0.1.0--0.2.0.sql .//sql/pg_duckdb--0.1.0.sql .//sql/pg_duck
db--0.2.0--0.3.0.sql '/home/username/projects/postgresql17-pg_duckdb/BUILDROOT/postgresql17-pg_duckdb-0.0.1-4.g35026b3.el9
.x86_64/usr/pgsql-17/share/extension/'
Live child 0x563c6f6cfc50 (install) PID 1987558
Reaping winning child 0x563c6f6cfc50 PID 1987558
/usr/bin/mkdir -p '/home/username/projects/postgresql17-pg_duckdb/BUILDROOT/postgresql17-pg_duckdb-0.0.1-4.g35026b3.el9.x86
_64/usr/pgsql-17/lib/bitcode/pg_duckdb'
Live child 0x563c6f6cfc50 (install) PID 1987559
Reaping winning child 0x563c6f6cfc50 PID 1987559
# ! IMPORTANT LINES !
/usr/bin/mkdir -p
Live child 0x563c6f6cfc50 (install) PID 1987560
/usr/bin/mkdir: missing operand
# ! END OF IMPORTANT LINES
Try '/usr/bin/mkdir --help' for more information.
Reaping losing child 0x563c6f6cfc50 PID 1987560
make: *** [/usr/pgsql-17/lib/pgxs/src/makefiles/pgxs.mk:246: install] Error 1
Removing child 0x563c6f6cfc50 PID 1987560 from chain.
```

### To Reproduce

```
export PATH=$PATH:/usr/pgsql-$PGVERSION/bin/

/bin/make
```

### OS:

Linux RHEL 9

### pg_duckdb Version (if built from source use commit hash):

v0.3.1

### Postgres Version (if built from source use commit hash):

pg16, pg17

### Hardware:

_No response_

### Full Name:

Sebastian Slanitsch

### Affiliation:

BMLV

### What is the latest build you tested with? If possible, we recommend testing with the latest nightly build.

I have tested with a stable release

### Did you include all relevant data sets for reproducing the issue?

Yes

### Did you include all code required to reproduce the issue?

- [x] Yes, I have

### Did you include all relevant configuration (e.g., CPU architecture, Linux distribution) to reproduce the issue?

- [x] Yes, I have