[REDIV-327] Fix 29 Dependabot alerts — bump Python 3.7→3.11, update all deps

- Bump Python requirement from 3.7 (EOL) to 3.11
- Add .tool-versions pinned to python 3.11.15 (asdf)
- flask >=3.0.3 → resolves to 3.1.3 (fixes alerts #10, #39)
- requests >=2.32.3 → resolves to 2.34.2 (fixes alerts #11, #23, #30, #40)
- python-dotenv >=1.0.2 → resolves to 1.2.2 (fixes alert #41)
- Regenerate Pipfile.lock — indirect deps resolve to safe versions:
  werkzeug 3.1.8 (fixes alerts #7,8,22,26,33,37,38)
  jinja2 3.1.6 (fixes alerts #19,21,28,29)
  urllib3 2.7.0 (fixes alerts #14,17,24,32,34,35,36,42)
  certifi 2026.7.22 (fixes alerts #6,13)
  idna 3.18 (fixes alerts #20,43)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: pcor-neoword

.tool-versions

@@ -0,0 +1 @@
+python 3.11.15

Pipfile

@@ -6,10 +6,10 @@ verify_ssl = true
 [dev-packages]
 
 [packages]
-flask = "*"
-requests = "*"
+flask = ">=3.0.3"
+requests = ">=2.32.3"
 requests-auth = "*"
-python-dotenv = "*"
+python-dotenv = ">=1.0.2"
 
 [requires]
-python_version = "3.7"
+python_version = "3.11"