chore(ci): pin the library version being built (#7255)

There are no code changes in `1.20.5` only packaging updates so we can
safely use the previous tracer version. This allows us to rapidly get
fix `1.20.5` out without waiting for the corresponding PyPI build to
finish which takes 4+ hours.

The risk is that users who are confused when manually specifying version
`1.20.5` in their K8s chart or deb/rpm install will see ``ddtrace``
version [`1.20.4`](https://pypi.org/project/ddtrace/1.20.4/) installed
instead. There is no harm as the 1.20.5 release is only fixing a
packaging issue for the library injection packages.

This change will be reverted as soon as `1.20.5` is released to ensure
subsequent `1.20` releases include the code changes to the library.

Author: Kyle-Verhoog

.gitlab/build-deb-rpm.sh

@@ -23,7 +23,7 @@ echo `pwd`
     --python-version=3.9 \
     --python-version=3.8 \
     --python-version=3.7 \
-    --ddtrace-version=$PYTHON_PACKAGE_VERSION  \
+    --ddtrace-version=1.20.4 \
     --arch x86_64 \
     --arch aarch64 \
     --platform musllinux_1_1 \

lib-injection/Dockerfile

@@ -15,7 +15,7 @@ RUN python3 dl_wheels.py \
         --python-version=3.9 \
         --python-version=3.8 \
         --python-version=3.7 \
-        --ddtrace-version=${DDTRACE_PYTHON_VERSION} \
+        --ddtrace-version=1.20.4 \
         --arch x86_64 \
         --arch aarch64 \
         --platform musllinux_1_1 \

releasenotes/notes/lib-inject-version-9236836076cc3c79.yaml

@@ -0,0 +1,5 @@
+---
+issues:
+  - |
+    lib-injection: The v1.20.5 release version has no library code changes and
+      will install the v1.20.4 version of `ddtrace``.